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<div id="contentSub"><div id="mw-content-subtitle"><div class="subpages">< <bdi dir="ltr"><a href="/wiki/Help:Cite_errors" title="Help:Cite errors">Help:Cite errors</a></bdi></div></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><style data-mw-deduplicate="TemplateStyles:r1238436933">.mw-parser-output .ombox{margin:4px 0;border-collapse:collapse;border:1px solid #a2a9b1;background-color:var(--background-color-neutral-subtle,#f8f9fa);box-sizing:border-box;color:var(--color-base,#202122)}.mw-parser-output .ombox.mbox-small{font-size:88%;line-height:1.25em}.mw-parser-output .ombox-speedy{border:2px solid #b32424;background-color:#fee7e6}.mw-parser-output .ombox-delete{border:2px solid #b32424}.mw-parser-output .ombox-content{border:1px solid #f28500}.mw-parser-output .ombox-style{border:1px solid #fc3}.mw-parser-output .ombox-move{border:1px solid #9932cc}.mw-parser-output .ombox-protection{border:2px solid #a2a9b1}.mw-parser-output .ombox .mbox-text{border:none;padding:0.25em 0.9em;width:100%}.mw-parser-output .ombox .mbox-image{border:none;padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .ombox .mbox-imageright{border:none;padding:2px 0.9em 2px 0;text-align:center}.mw-parser-output .ombox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ombox .mbox-invalid-type{text-align:center}@media(min-width:720px){.mw-parser-output .ombox{margin:4px 10%}.mw-parser-output .ombox.mbox-small{clear:right;float:right;margin:4px 0 4px 1em;width:238px}}body.skin--responsive .mw-parser-output table.ombox img{max-width:none!important}@media screen{html.skin-theme-clientpref-night .mw-parser-output .ombox-speedy{background-color:#310402}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .ombox-speedy{background-color:#310402}}</style><table class="plainlinks ombox ombox-notice" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Twemoji_1f527.svg/30px-Twemoji_1f527.svg.png" decoding="async" width="30" height="30" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Twemoji_1f527.svg/45px-Twemoji_1f527.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Twemoji_1f527.svg/60px-Twemoji_1f527.svg.png 2x" data-file-width="512" data-file-height="512"/></span></span></td><td class="mbox-text"><div style="padding-top: 6px; padding-bottom: 5px;"><b>This help page is a <a href="/wiki/Wikipedia:Project_namespace#Wikipedia_how-to_and_information_pages" title="Wikipedia:Project namespace">how-to guide</a>.</b><br/><div style="font-size: 90%;">It explains concepts or processes used by the Wikipedia community. It is not one of <a href="/wiki/Wikipedia:Policies_and_guidelines" title="Wikipedia:Policies and guidelines">Wikipedia's policies or guidelines</a>, and may reflect varying levels of <a href="/wiki/Wikipedia:Consensus" title="Wikipedia:Consensus">consensus</a>.</div></div></td><td class="mbox-imageright"><style data-mw-deduplicate="TemplateStyles:r1252059228">.mw-parser-output .module-shortcutboxplain{float:right;margin:0 0 0 1em;border:1px solid var(--border-color-base,#a2a9b1);background-color:var(--background-color-base,#fff);padding:0.3em 0.6em 0.2em 0.6em;text-align:center;font-size:85%}.mw-parser-output .module-shortcutboxleft{float:left;margin:0 1em 0 0}.mw-parser-output .module-shortcutlist{display:inline-block;border-bottom:1px solid var(--border-color-base,#a2a9b1);margin-bottom:0.2em}.mw-parser-output .module-shortcutboxplain ul{font-weight:bold}.mw-parser-output .module-shortcutanchordiv{position:relative;top:-3em}.mw-parser-output li .module-shortcutanchordiv{float:right}.mw-parser-output .mbox-imageright .module-shortcutboxplain{padding:0.4em 1em 0.4em 1em;line-height:1.3;margin:0}</style><div class="module-shortcutanchordiv"><span id="H:CERDK"></span></div><div class="module-shortcutboxplain noprint" role="note"><div class="module-shortcutlist"><a href="/wiki/Wikipedia:Shortcut" title="Wikipedia:Shortcut">Shortcut</a></div><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style><div class="plainlist"><ul><li><span class="plainlinks"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=H:CERDK&redirect=no">H:CERDK</a></span></li></ul></div></div></td></tr></tbody></table> <p>This page will help you to fix the <a href="/wiki/Help:Cite_errors" title="Help:Cite errors">cite error message</a>: <br/> <br/> <strong class="error">The named reference "$1" was defined multiple times with different content (see the <a class="mw-selflink selflink">help page</a>).</strong> <br/> <br/> </p> <ul><li><span style="font-size:95%"> If you have read this help page and find something missing or confusing, please discuss it at the <a href="/wiki/Help_talk:Cite_errors" title="Help talk:Cite errors">main talk page</a>.</span></li> <li><span style="font-size:95%"> Please reference this page and the page where you have the problem so we can understand your issues.</span></li> <li><span style="font-size:95%">For basic information on the footnotes system, see <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">Referencing for beginners</a>; for advanced help, see <a href="/wiki/Help:Footnotes" title="Help:Footnotes">Footnotes</a>.</span></li></ul> <meta property="mw:PageProp/toc"/> <div class="mw-heading mw-heading2 ext-discussiontools-init-section"><h2 id="Overview" data-mw-thread-id="h-Overview"><span data-mw-comment-start="" id="h-Overview"></span>Overview<span data-mw-comment-end="h-Overview"></span></h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=1" title="Edit section: Overview"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Wikipedia:REFNAME" class="mw-redirect" title="Wikipedia:REFNAME">WP:REFNAME</a></div> <p>If you are going to reference the same source multiple times, Wikipedia allows you to name those sources so you can just refer to a source named "foo" rather than having to recreate all of the details about the citation (the author, the title, etc.) over and over. The name is created like this: </p> <dl><dd><code class="nowrap" style=""><ref name="foo"><i>content</i></ref></code></dd></dl> <p>Then, to invoke that footnote you have named <i>foo</i>, just type this: </p> <dl><dd><code class="nowrap" style=""><ref name="foo" /></code></dd></dl> <p>The <i>content</i> (the details of the citation) of the reference that has been named "foo" is thus defined only once but can be reused over and over. </p> <div class="mw-heading mw-heading2 ext-discussiontools-init-section"><h2 id="Issues_and_resolution" data-mw-thread-id="h-Issues_and_resolution"><span data-mw-comment-start="" id="h-Issues_and_resolution"></span>Issues and resolution<span data-mw-comment-end="h-Issues_and_resolution"></span></h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=2" title="Edit section: Issues and resolution"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The error happens when a named reference is defined multiple times with different content. For example, first <code class="nowrap" style=""><ref name="foo"><i>content1</i></ref></code> and later <code class="nowrap" style=""><ref name="foo"><i>content2</i></ref></code>, where <code>"foo"</code> is repeated but <i>content1</i> and <i>content2</i> are different. The purpose of named references is to be able to invoke them elsewhere with <code class="nowrap" style=""><ref name="foo" /></code>, but there must be a unique definition of the ref name "foo". </p><p>If the references with <i>content1</i> and <i>content2</i> are meant to be different then change one of the ref names, for example <code>name="bar"</code> instead of <code>name="foo"</code>. If the reference is not meant to be invoked elsewhere then it can also be made unnamed by removing <code>name="foo"</code>, but this is not necessary. </p><p>If the references are meant to be the same then replace one of the definitions by <code class="nowrap" style=""><ref name="foo" /></code> to invoke the other definition. It may technically work to make two identical definitions but this should <i>not</i> be done. It causes confusion and will recreate the error if somebody later changes one of the definitions without making the same change to the other. </p><p>The error can also happen with empty ref names like <code class="nowrap" style=""><ref name=""><i>content</i></ref></code> or <code class="nowrap" style=""><ref name><i>content</i></ref></code>. Ref names should not be empty. Either add a name or remove <code>name=""</code>. </p><p>Ref names may be generated by a template and produce names not in the wikitext. For example, <code>{{<a href="/wiki/Template:Sfn" title="Template:Sfn">sfn</a>|Stokes|1979|p=2}}</code> and <code>{{<a href="/wiki/Template:Sfn" title="Template:Sfn">sfn</a>|Stokes|1979|pp=2}}</code> may both produce references of form <code><ref name="FOOTNOTEStokes19792">...</ref></code>, causing the error message to use the ref name "FOOTNOTEStokes19792". <code>p=</code> is intended for a single page and <code>pp=</code> for a range. <code>ps=</code> must have the same value in each use of <code>{{<a href="/wiki/Template:Sfn" title="Template:Sfn">sfn</a>}}</code> where the other parameters are identical. An assigned value in <code>ps=</code> cannot be combined with an omitted <code>ps=</code> elsewhere on the page. If there is a blank <code>ps=</code> then remove it. </p><p>See also <a class="mw-selflink-fragment" href="#Templates">Technical Templates</a> below. </p><p>Whole references may be transcluded from other pages. When the "Edit" or "Edit source" tab at top of a page is clicked, the bottom of the window will say "Pages transcluded onto the current version of this page". Click the text if no list is shown. Articles are more likely than other pages to contain named references. </p><p>The ref name in the error message may have replaced spaces by underscores and converted some special characters. </p> <div class="mw-heading mw-heading3"><h3 id="Names" data-mw-thread-id="h-Names-Issues_and_resolution"><span data-mw-comment-start="" id="h-Names-Issues_and_resolution"></span>Names<span data-mw-comment-end="h-Names-Issues_and_resolution"></span></h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=3" title="Edit section: Names"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Names for footnotes and groups must follow these rules: </p> <ul><li>Names are case-sensitive. Please do not use raNdOM capitalization.</li> <li>Names <strong>must not</strong> be purely numeric; the software will accept something like <code>":31337"</code> (which is punctuation plus a number), but it will ignore <code>"31337"</code> (purely numeric).</li> <li>Names should have semantic value, so that they can be more easily distinguished from each other by human editors who are looking at the wikitext. This means that ref names like <code>"Nguyen 2010"</code> are preferred to names like <code>":31337"</code>.</li> <li>Names must be unique. You may not use the same name to define different groups or footnotes. Try to avoid picking a name that someone else is likely to choose for a new citation, such as <code>":0"</code> or <code>"NYT"</code>.</li> <li>Please consider keeping reference names short, simple, and restricted to the standard <a href="/wiki/English_alphabet" title="English alphabet">English alphabet</a> and numerals. If spaces are used, the following technical restrictions become relevant: <ul><li>Quotation marks are preferred but optional if the only characters used are letters <code>A–Z</code>, <code>a–z</code>, digits <code>0–9</code>, and the symbols <code style="word-break: break-all;">!$%&()*,-.:;<@[]^_`{|}~</code>. That is, all printable ASCII characters except <code style="word-break: break-all;">#"'/=<>?\</code> and space.</li> <li>Inclusion of any other characters, <em>including spaces</em>, requires that the reference name be enclosed in quotes; for example, <code>name="John Smith"</code>. But quote-enclosed reference names may not include a less-than sign (<code><</code>) or a double straight quote symbol (<code>"</code>), which may however be included by <a href="/wiki/Escape_sequence" title="Escape sequence">escaping</a> as <code>&lt;</code> and <code>&quot;</code> respectively.</li> <li>The quote marks must be the standard, straight, double quotation marks (<code>"</code>); curly or other quotes will be parsed as part of the reference name.</li></ul></li> <li>You may optionally provide reference names even when the reference name is not required. This makes later re-use of the sourced reference easier.</li></ul> <div class="mw-heading mw-heading2 ext-discussiontools-init-section"><h2 id="Sfn" data-mw-thread-id="h-Sfn"><span data-mw-comment-start="" id="h-Sfn"></span>Sfn<span data-mw-comment-end="h-Sfn"></span></h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=4" title="Edit section: Sfn"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>If two or more calls to <code>{{<a href="/wiki/Template:Sfn" title="Template:Sfn">sfn</a>}}</code> use the same citation parameters, that is, if the author(s), year, and page number(s) are all identical, but there is some other difference, such as a use of <code>pp=</code> vs <code>p=</code>, or a use of <code>ps=</code> in one but not the other, this issue will arise. </p><p>The solution is to make the calls identical. If the <code>ps=</code> parameter was being used to include a quote or other extended content, use <code>{{<a href="/wiki/Template:Harvnb" class="mw-redirect" title="Template:Harvnb">harvnb</a>}}</code> inside a <code class="nowrap" style=""><ref>...</ref></code> construct with the quote after the template but inside the ref tag structure. </p> <div class="mw-heading mw-heading2 ext-discussiontools-init-section"><h2 id="Nested_footnotes" data-mw-thread-id="h-Nested_footnotes"><span data-mw-comment-start="" id="h-Nested_footnotes"></span>Nested footnotes<span data-mw-comment-end="h-Nested_footnotes"></span></h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=5" title="Edit section: Nested footnotes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>If there are <a href="/wiki/Wikipedia:Nesting_footnotes" title="Wikipedia:Nesting footnotes">nested footnotes</a>, i.e. a reference within another reference, then the error can occur even if two definitions have identical text. Example where <span class="nowrap">{{</span><a href="/wiki/Template:Sfn" title="Template:Sfn">sfn</a><span class="nowrap">}}</span> will create a ref name with another reference inside it: </p> <pre><ref name="Buna">Advance to Buna</ref> {{sfn|Blakeley|1956|ps=. Cited in Advance to Buna.<ref name=Buna />}} {{sfn|Blakeley|1956|ps=. Cited in Advance to Buna.<ref name=Buna />}} </pre> <p>Removing the inner reference will fix the error. </p> <div class="mw-heading mw-heading2 ext-discussiontools-init-section"><h2 id="Examples" data-mw-thread-id="h-Examples"><span data-mw-comment-start="" id="h-Examples"></span>Examples<span data-mw-comment-end="h-Examples"></span></h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=6" title="Edit section: Examples"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238436933"><table class="plainlinks ombox ombox-notice" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><a href="/wiki/File:Check-Reference.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/Check-Reference.svg/40px-Check-Reference.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/34/Check-Reference.svg/60px-Check-Reference.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/34/Check-Reference.svg/80px-Check-Reference.svg.png 2x" data-file-width="48" data-file-height="48"/></a></span></td><td class="mbox-text">The content of this message is dependent on the language setting in <a href="/wiki/Special:Preferences" title="Special:Preferences">Special:Preferences</a>. You can test how the error messages look in the most popular languages with these links: <style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}</style><div class="hlist noprint plainlinks nowraplinks"> <ul><li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=bn">বাংলা</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=en">English</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=es">español</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=en-gb">British English</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=fr">français</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=pt-br">português do Brasil</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=ru">русский</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=de">Deutsch</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=id">Bahasa Indonesia</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=ar">العربية</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=zh-cn">中文（中国大陆）</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=ro">română</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=it">italiano</a></li> <li><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&uselang=tr">Türkçe</a></li></ul> </div></td></tr></tbody></table> <p><span class="example" style="font-family: Georgia, 'DejaVu Serif', serif; color: var(--color-content-added, #006400);">Here the reference named <i>ipsum</i> was defined twice, but the second definition's content differs from the first (only the first definition is taken):</span> </p> <style data-mw-deduplicate="TemplateStyles:r1195917819">.mw-parser-output .pre-borderless{border:none}</style><pre class="pre">Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.<ref name="ipsum">Reference 1</ref> Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.<ref name="ipsum">Reference 2</ref> Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.<ref name="ipsum"/> Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. ==References== {{reflist}}</pre> <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.<sup id="cite_ref-ipsum_1-0" class="reference"><a href="#cite_note-ipsum-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.<sup id="cite_ref-ipsum_1-1" class="reference"><a href="#cite_note-ipsum-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.<sup id="cite_ref-ipsum_1-2" class="reference"><a href="#cite_note-ipsum-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. </p> <style data-mw-deduplicate="TemplateStyles:r1236298596">.mw-parser-output .fake-heading{color:var(--color-emphasized,#000000);background:none;margin:0;overflow:hidden;padding-bottom:0.17em;page-break-after:avoid;padding-top:0.5em}.mw-parser-output .fake-heading.h1,.mw-parser-output .fake-heading.h2{border-bottom:1px solid var(--border-color-base,#a2a9b1);margin-bottom:0.25em;margin-top:1em;padding:0;font-family:"Linux Libertine","Georgia","Times","Source Serif Pro",serif;line-height:1.375}body.skin-monobook .mw-parser-output .fake-heading.h1,body.skin-monobook .mw-parser-output .fake-heading.h2{font-family:inherit;line-height:inherit}body.skin-timeless .mw-parser-output .fake-heading.h1,body.skin-timeless .mw-parser-output .fake-heading.h2{border-bottom:3px solid #c8ccd1}.mw-parser-output .fake-heading.h1{font-size:1.8em}body.skin-timeless .mw-parser-output .fake-heading.h1{font-size:2em}.mw-parser-output .fake-heading.h2{font-size:1.5em}body.skin-timeless .mw-parser-output .fake-heading.h2{font-size:1.8em}.mw-parser-output .fake-heading.h3,.mw-parser-output .fake-heading.h4,.mw-parser-output .fake-heading.h5,.mw-parser-output .fake-heading.h6{font-weight:bold;margin-top:0.3em;margin-bottom:0;padding-bottom:0;line-height:1.6}.mw-parser-output .fake-heading.h3{font-size:1.2em}.mw-parser-output .fake-heading.h4{font-size:100%}</style><div class="fake-heading h3">References</div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: close;"> <ol class="references"> <li id="cite_note-ipsum-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-ipsum_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ipsum_1-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-ipsum_1-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">Reference 1 <span class="error mw-ext-cite-error" lang="en" dir="ltr">Cite error: The named reference "ipsum" was defined multiple times with different content (see the <a class="mw-selflink selflink">help page</a>).</span></span> </li> </ol></div> <div class="mw-heading mw-heading2 ext-discussiontools-init-section"><h2 id="Technical" data-mw-thread-id="h-Technical"><span data-mw-comment-start="" id="h-Technical"></span>Technical<span data-mw-comment-end="h-Technical"></span></h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=7" title="Edit section: Technical"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Pages with this error message are placed into <a href="/wiki/Category:Pages_with_duplicate_reference_names" title="Category:Pages with duplicate reference names">Pages with duplicate reference names</a>. The system message page is at <a href="/wiki/MediaWiki:Cite_error_references_duplicate_key" title="MediaWiki:Cite error references duplicate key">Cite error references duplicate key</a>. </p> <div class="mw-heading mw-heading3"><h3 id="Templates" data-mw-thread-id="h-Templates-Technical"><span data-mw-comment-start="" id="h-Templates-Technical"></span>Templates<span data-mw-comment-end="h-Templates-Technical"></span></h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Help:Cite_errors/Cite_error_references_duplicate_key&action=edit&section=8" title="Edit section: Templates"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1227084136">.mw-parser-output .tracked{float:right;clear:right;margin:0 0 1em 1em;width:12em;border:1px solid #72777d;border-radius:2px;background-color:var(--background-color-interactive,#EAECF0);color:var(--color-base,#202122);font-size:85%;text-align:center;padding:0.5em}.mw-parser-output .tracked-url{font-weight:bold}.mw-parser-output .tracked-closure{color:black;font-weight:bold;text-transform:uppercase}.mw-parser-output .tracked-resolved{color:green}</style><div role="note" class="tracked plainlinks mw-trackedTemplate">Tracked in <a href="https://phabricator.wikimedia.org/" class="extiw" title="phabricator:">Phabricator</a><br/><span class="tracked-url"><a href="https://phabricator.wikimedia.org/T39256" class="extiw" title="phabricator:T39256"><span class="trakfab-T39256"> Task T39256</span></a></span><br/></div> <p>In order to include variable data within a reference tag such as <code><ref ref_content name=ref_name></code>, the <code>#tag</code> parser function must be used. Currently <code>#tag</code> only supports balanced tags, not a singular tag, thus <code><tag_type element /></code> cannot normally be used in a template unless the element is hard coded. </p><p>However, Cite has been modified since 2008<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> to treat <code><ref name="ref-foo"></ref></code> identically to <code><ref name="ref-foo" /></code>. Note that there cannot be even a space between the <code><ref . . .></code> and the <code></ref></code>, otherwise this will result in definition of the reference named "ref-foo" to be " ", which if meant to be second reference by name to an existing reference will cause a duplicate definition error. Correct code to produce a singular tag will look like <code>{{#tag:ref ||name={{{parameter}}}}}</code>, that is, no space between the two "|"s. </p> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output 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dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="Wikipedia_referencing" style="padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output 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0.25em"> <ul><li><a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">Verifiability</a></li> <li><a href="/wiki/Wikipedia:No_original_research" title="Wikipedia:No original research">No original research</a></li> <li><a href="/wiki/Wikipedia:Biographies_of_living_persons" title="Wikipedia:Biographies of living persons">Biographies of living persons</a> <ul><li><a href="/wiki/Wikipedia:Identifying_reliable_sources_(medicine)" title="Wikipedia:Identifying reliable sources (medicine)">Medicine</a></li></ul></li> <li><a href="/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources">Citing sources</a></li> <li><a href="/wiki/Wikipedia:Scientific_citation_guidelines" title="Wikipedia:Scientific citation guidelines">Scientific citations</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">General advice</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">Citation needed</a></li> <li><a href="/wiki/Wikipedia:Combining_sources" title="Wikipedia:Combining sources">Combining sources</a></li> <li><a href="/wiki/Wikipedia:Offline_sources" title="Wikipedia:Offline sources">Offline sources</a></li> <li><a href="/wiki/Help:Overview_of_referencing_styles" title="Help:Overview of referencing styles">Referencing styles</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources">Citing sources</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Help:Citation_Style_1" title="Help:Citation Style 1">Citation Style 1</a></li> <li><a href="/wiki/Help:Citation_Style_2" title="Help:Citation Style 2">Citation Style 2</a></li> <li><a href="/wiki/Help:Citation_Style_Vancouver" title="Help:Citation Style Vancouver">Citation Style Vancouver</a></li> <li><a href="/wiki/Category:Bluebook_style_citation_templates" title="Category:Bluebook style citation templates">Bluebook</a></li> <li><a href="/wiki/Category:Comics_citation_templates" title="Category:Comics citation templates">Comics</a></li> <li><a href="/wiki/Wikipedia:Citation_templates" title="Wikipedia:Citation templates">Citation templates</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Wikipedia:Inline_citation" title="Wikipedia:Inline citation">Inline citations</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Help:Footnotes" title="Help:Footnotes">Footnotes</a></li> <li><a href="/wiki/Wikipedia:Manual_of_Style#Punctuation_and_footnotes" title="Wikipedia:Manual of Style">Punctuation and footnotes</a></li> <li><a href="/wiki/Help:Shortened_footnotes" title="Help:Shortened footnotes">Shortened footnotes</a></li> <li><a href="/wiki/Wikipedia:Nesting_footnotes" title="Wikipedia:Nesting footnotes">Nesting footnotes</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">Help for beginners</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Help:Reftags" title="Help:Reftags">Reference-tags</a></li> <li><a href="/wiki/Help:Citations_quick_reference" title="Help:Citations quick reference">Citations quick reference</a></li> <li><a href="/wiki/Help:Introduction_to_referencing_with_Wiki_Markup/1" title="Help:Introduction to referencing with Wiki Markup/1">Introduction to referencing</a></li> <li><a href="/wiki/Help:Referencing_for_beginners_with_citation_templates" title="Help:Referencing for beginners with citation templates">Referencing with citation templates</a></li> <li><a href="/wiki/Help:Referencing_for_beginners_without_using_templates" title="Help:Referencing for beginners without using templates">Referencing without using templates</a></li> <li><a href="/wiki/Wikipedia:References_dos_and_don%27ts" title="Wikipedia:References dos and don'ts">Referencing dos and don'ts</a></li> <li><a href="/wiki/Wikipedia:Citing_Wikipedia" title="Wikipedia:Citing Wikipedia">Citing Wikipedia</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Advanced help</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Help:Cite_link_labels" title="Help:Cite link labels">Cite link labels</a></li> <li><a href="/wiki/Help:Cite_errors" title="Help:Cite errors">Cite errors</a></li> <li><a href="/wiki/Help:Citation_merging" title="Help:Citation merging">Citation merging (bundling)</a></li> <li><a href="/wiki/Help:Cite_messages" title="Help:Cite messages">Cite messages</a></li> <li><a href="/wiki/Help:Converting_between_references_formats" title="Help:Converting between references formats">Converting between references formats</a></li> <li><a href="/wiki/Help:Reference_display_customization" title="Help:Reference display customization">Reference display customization</a></li> <li><a href="/wiki/Help:References_and_page_numbers" title="Help:References and page numbers">References and page numbers</a></li> <li><a href="/wiki/Wikipedia:Guidance_on_source_reviewing_at_FAC" title="Wikipedia:Guidance on source reviewing at FAC">Guidance on source reviewing at FAC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Category:Footnote_templates" title="Category:Footnote templates">Footnote templates</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Template:Citation_Style_documentation" title="Template:Citation Style documentation">Citation Style documentation</a></li> <li><a href="/wiki/Template:Multiple_references" class="mw-disambig" title="Template:Multiple references">Multiple references</a></li> <li><span class="nowrap">{{</span><a href="/wiki/Template:Reflist" title="Template:Reflist">Reflist</a><span class="nowrap">}}</span></li> <li><span class="nowrap">{{</span><a href="/wiki/Template:Refbegin" title="Template:Refbegin">Refbegin</a><span class="nowrap">}}</span></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Help:Find_sources" title="Help:Find sources">Find references </a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Wikipedia:FIND" class="mw-redirect" title="Wikipedia:FIND">How to find sources</a></li> <li><a href="/wiki/Wikipedia:List_of_bibliographies" title="Wikipedia:List of bibliographies">Bibliographies</a></li> <li><a href="/wiki/Wikipedia:The_Wikipedia_Library" title="Wikipedia:The Wikipedia Library">Wikipedia Library</a></li> <li><a href="/wiki/Wikipedia:WikiProject_Resource_Exchange/Resource_Request" title="Wikipedia:WikiProject Resource Exchange/Resource Request">Resource Exchange</a></li> <li><a href="/wiki/Wikipedia:Reference_desk" title="Wikipedia:Reference desk">Reference Desk</a></li> <li><a href="/wiki/Wikipedia:Book_sources" title="Wikipedia:Book sources">Book Sources</a></li> <li><a href="/wiki/Wikipedia:Free_English_newspaper_sources" title="Wikipedia:Free English newspaper sources">Free newspaper sources</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Help:Citation_tools" title="Help:Citation tools">Citation tools</a><br/>(External links)</th><td class="navbox-list-with-group navbox-list navbox-odd" 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