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<h2 id="code-format">Code format</h2> <p>An ISSN is an eight-digit code, divided by a hyphen into two four-digit numbers.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> The last digit, which may be zero through nine or an X, is a <a href="/facts/Check_digit/qMlumJpU">check digit</a>, so the ISSN is uniquely represented by its first seven digits. Formally, the general form of the ISSN (also named "ISSN structure" or "ISSN syntax") can be expressed as follows:<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> NNNN-NNNC <p>where N is in the set {<i>0,1,2,...,9</i>}, a decimal digit character, and C is in {<i>0,1,2,...,9,X</i>}; or by a <a href="/facts/Perl_Compatible_Regular_Expressions/JXYJEsUq">Perl Compatible Regular Expressions</a> (PCRE) <a href="/facts/Regular_expression/KFL3veHX">regular expression</a>: </p> ^[0-9]{4}-[0-9]{3}[0-9X]$. <p>For example, the ISSN of the journal <i><a href="/facts/Hearing_Research/fEVjIpgs">Hearing Research</a></i>, is 0378-5955, where the final 5 is the check digit, that is C=5. To calculate the check digit, the following algorithm may be used: </p> Each of the first seven digits of the ISSN is multiplied by its position in the number, counting from the right, that is, 8, 7, 6, 5, 4, 3, and 2, respectively, and the resulting products are added: <p> 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 . {\displaystyle {\begin{aligned}&0\cdot 8+3\cdot 7+7\cdot 6+8\cdot 5+5\cdot 4+9\cdot 3+5\cdot 2\\&=0+21+42+40+20+27+10\\&=160\;.\end{aligned}}} </p><p>The <a href="/facts/Remainder/wCmbYeeh">remainder</a> of this sum <a href="/facts/Modulo/5tKQmM76">modulo</a> 11 is then calculated: 160 11 = 14 remainder 6 = 14 + 6 11 {\displaystyle {\frac {160}{11}}=14{\mbox{ remainder }}6=14+{\frac {6}{11}}} </p><p>If there is no remainder, the check digit is 0; otherwise the remainder is subtracted from 11. If the result is less than 10, it yields the check digit: 11 − 6 = 5 . {\displaystyle 11-6=5\;.} Thus, in this example, the check digit C is 5. </p> If the result is 10 (that is, if the remainder is 1), the check digit is an uppercase X (like a <a href="/facts/Roman_numerals/7BA8nn78">Roman ten</a>). <p>To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by their position in the number, counting from the right. (If the check digit is X, add 10 to the sum.) The remainder of the sum modulo 11 must be 0. There is an online ISSN checker that can validate an ISSN, based on the above algorithm.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> </p> <h3>In EANs</h3> <p>ISSNs can be encoded in <a href="/facts/International_Article_Number_(EAN)/1BqwBFU2">EAN-13 bar codes</a> with a 977 "country code" (compare the 978 "<a href="/facts/Bookland/4RwD7ejm">bookland</a>" country code for <a href="/facts/ISBN/15AdSPa9">ISBNs</a>), followed by the 7 main digits of the ISSN (the check digit is not included), followed by 2 publisher-defined digits, followed by the EAN check digit (in most cases, this will not match the ISSN check digit, since they are each calculated in a different way).<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p> <h2 id="code-assignment-maintenance-and-look-up">Code assignment, maintenance and look-up</h2> <p>ISSN codes are assigned by a network of ISSN National Centres, usually located at <a href="/facts/National_library/6rlUEkGs">national libraries</a> and coordinated by the ISSN International Centre based in <a href="/facts/Paris/DrNHpwnA">Paris</a>. The International Centre is an <a href="/facts/Intergovernmental_organization/5ELbyRm6">intergovernmental organization</a> created in 1974 through an agreement between <a href="/facts/UNESCO/QSbkRv3o">UNESCO</a> and the French government. </p> <h3>Linking ISSN</h3> <p><i>ISSN-L</i> is a <a href="/facts/Unique_identifier/NMcgc7qX">unique identifier</a> for all versions of the serial containing the same <a href="/facts/Content_(media)/eW5vd3Dr">content</a> across different media. As defined by <i>ISO 3297:2007</i>, the "linking ISSN (ISSN-L)" provides a mechanism for collocation or linking among the different media versions of the same continuing resource. The <i>ISSN-L</i> is one of a serial's existing ISSNs, so does not change the use or assignment of "ordinary" ISSNs;<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> it is based on the ISSN of the first published medium version of the publication. If the print and online versions of the publication are published at the same time, the ISSN of the print version is chosen as the basis of the <i>ISSN-L</i>. </p><p>With <i>ISSN-L</i> is possible to designate one single ISSN for all those media versions of the title. The use of <i>ISSN-L</i> facilitates search, retrieval and delivery across all media versions for services like <a href="/facts/OpenURL/A3jvEf5a">OpenURL</a>, <a href="/facts/Library_catalogue/mk474y74">library catalogues</a>, <a href="/facts/Search_engine/SRntsbz2">search engines</a> or <a href="/facts/Knowledge_base/zKXdqQjH">knowledge bases</a>. </p> <h3>Register</h3> <p>The International Centre maintains a database of all ISSNs assigned worldwide, the <i>ISDS Register</i> (International Serials Data System), otherwise known as the <i>ISSN Register</i>. At the end of 2016, the ISSN Register contained records for 1,943,572 items.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> The Register is not freely available for interrogation on the web, but is available by subscription. </p> <ul><li>The print version of a serial typically will include the ISSN code as part of the publication information.</li> <li>Most serial websites contain ISSN code information.</li> <li>Derivative lists of publications will often contain ISSN codes; these can be found through on-line searches with the ISSN code itself or serial title.</li> <li><a href="/facts/WorldCat/TLr4VYzI">WorldCat</a> permits searching its catalog by ISSN, by entering "issn:" before the code in the query field. One can also go directly to an ISSN's record by appending it to "https://www.worldcat.org/ISSN/", e.g. <a href="https://www.worldcat.org/ISSN/1021-9749">n2:1021-9749 – Search Results</a>. This does not query the ISSN Register itself, but rather shows whether any WorldCat library holds an item with the given ISSN.</li></ul> <h2 id="comparison-with-other-identifiers">Comparison with other identifiers</h2> <p>ISSN and <a href="/facts/ISBN/15AdSPa9">ISBN</a> codes are similar in concept, where ISBNs are assigned to individual <a href="/facts/Book/Yylgt4AC">books</a>. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no <a href="/facts/Information/3LdrzXtJ">information</a> as to the <a href="/facts/Publisher/7g01YeYG">publisher</a> or its <a href="/facts/Location_(geography)/fXux5RaJ">location</a>. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. </p> <h3>Extensions</h3> <p>Since the ISSN applies to an entire serial, other identifiers have been built on top of it to allow references to specific volumes, articles, or other identifiable components (like the <a href="/facts/Table_of_contents/g9uVzwlq">table of contents</a>): the <a href="/facts/Publisher_Item_Identifier/lIAMekYo">Publisher Item Identifier</a> (PII) and the <a href="/facts/Serial_Item_and_Contribution_Identifier/wMqQMJ39">Serial Item and Contribution Identifier</a> (SICI). </p> <h3>Media versus content </h3> <p>Separate ISSNs are needed for serials in different media (except reproduction <a href="/facts/Microform/4VfjjRRG">microforms</a>). Thus, the <a href="/facts/Print_media/M1UE4TTp">print</a> and <a href="/facts/Electronic_media/IzPK2q4u">electronic media</a> versions of a serial need separate ISSNs,<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> and <a href="/facts/CD-ROM/JwuaYLJv">CD-ROM</a> versions and <a href="/facts/World_Wide_Web/wvnTrWFq">web</a> versions require different ISSNs. However, the same ISSN can be used for different file formats (e.g. <a href="/facts/PDF/C9Mn1vYL">PDF</a> and <a href="/facts/HTML/sSc3fT78">HTML</a>) of the same online serial. </p><p>This "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, and the Web, it makes sense to consider only <i>content</i>, independent of media. This "content-oriented identification" of serials was a <a href="/facts/Excess_demand/08r3vKHx">repressed demand</a> during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the <a href="/facts/Indecs_Content_Model/G9BsAJ6g">indecs Content Model</a> and its application, the <a href="/facts/Digital_object_identifier/muM9Etpq">digital object identifier</a> (DOI), an ISSN-independent initiative, consolidated in the 2000s. </p><p>Only later, in 2007, ISSN-L was defined in the new ISSN standard (ISO 3297:2007) as an "ISSN designated by the ISSN Network to enable collocation or versions of a continuing resource linking among the different media".<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p> <h2 id="use-in-urns">Use in URNs</h2> <p>An ISSN can be encoded as a <a href="/facts/Uniform_resource_name/DCaGkLLY">uniform resource name</a> (URN) by prefixing it with "urn:ISSN:".<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> For example, <a href="/facts/Rail_(magazine)/g458NMfj"><i>Rail</i></a> could be referred to as "urn:ISSN:0953-4563". URN namespaces are case-sensitive, and the ISSN namespace is all caps.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> If the checksum digit is "X" then it is always encoded in uppercase in a URN. </p> <h3>Problems</h3> <p>The URNs are content-oriented, but ISSN is media-oriented: </p> <ul><li>ISSN is not unique when the concept is "a journal is a set of contents, generally copyrighted content": the same journal (same contents and same copyrights) may have two or more ISSN codes. A URN needs to point to "unique content" (a "unique journal" as a "set of contents" reference).</li></ul> Example: <a href="/facts/Nature_(journal)/XmlJXkFx">Nature</a> has an ISSN for print, 0028-0836, and another for the same content on the Web, 1476-4687; only the oldest (0028-0836) is used as a <a href="/facts/Unique_identifier/NMcgc7qX">unique identifier</a>. As the ISSN is not unique, the <a href="/facts/U.S._National_Library_of_Medicine/Hzty0MCX">U.S. National Library of Medicine</a> needed to create, prior to 2007, the NLM Unique ID (JID).<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> <ul><li>ISSN does not offer <a href="/facts/Uniform_resource_name/DCaGkLLY">resolution mechanisms</a> like a <a href="/facts/Digital_object_identifier/muM9Etpq">digital object identifier</a> (DOI) or a URN does, so the DOI is used as a URN for articles, with (for historical reasons) no need for an ISSN's existence.</li></ul> Example: the DOI name "10.1038/nature13777" can be represented as an HTTP string by <i>https://doi.org/</i>10.1038/nature13777, and is <a href="/facts/URL_redirection/4o1p9l7C">redirected</a> (resolved) to the current article's page; but there is no ISSN online service, like http://dx.issn.org/, to resolve the ISSN of the journal (in this sample <a href="/facts/Nature_(journal)/XmlJXkFx">1476-4687</a>). <p>A unique URN for serials simplifies the search, recovery and delivery of data for various services including, in particular, <a href="/facts/Information_retrieval/MFSmpeNw">search systems</a> and <a href="/facts/Knowledge_base/zKXdqQjH">knowledge databases</a>.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> ISSN-L (see Linking ISSN above) was created to fill this gap. </p> <h2 id="media-category-labels">Media category labels</h2> <p>The two standard categories of media in which serials are most available are <i>print</i> and <i>electronic</i>. In <a href="/facts/Metadata/qt35z79C">metadata</a> contexts (e.g., <a href="/facts/JATS/3xJtJaRr">JATS</a>), these may have standard labels. </p> <h3>Print ISSN</h3> <p><i>p-ISSN</i> is a standard label for "Print ISSN", the ISSN for the <a href="/facts/Print_media/M1UE4TTp">print media</a> (paper) version of a serial. Usually it is the "default media" and so the "default ISSN". </p> <h3>Electronic ISSN </h3> <p><i>e-ISSN</i> (or <i>eISSN</i>) is a standard label for "Electronic ISSN", the ISSN for the <a href="/facts/Electronic_media/IzPK2q4u">electronic media</a> (online) version of a serial.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> </p> <h2 id="road">ROAD</h2> <ul><li><a href="/facts/ROAD%3a_Directory_of_Open_Access_Scholarly_Resources/DPAflDvU">ROAD: Directory of Open Access Scholarly Resources</a> [it] (est. 2013), produced by the <a href="/facts/ISSN_International_Centre/DPAflDvU">ISSN International Centre</a> and <a href="/facts/UNESCO/QSbkRv3o">UNESCO</a><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/CODEN/YmfJcNjb">CODEN</a></li> <li><a href="/facts/WorldCat/TLr4VYzI">WorldCat</a>—an ISSN-resolve service</li></ul> <h2 id="external-links">External links</h2> <a href="/facts/Wikidata/5Myy74K5">Wikidata</a> has the property: <ul><li> <i>ISSN (P236)</i> (see <a href="https://query.wikidata.org/embed.html#SELECT%20%3FWikidata_item_%20%3FWikidata_item_Label%20%3Fvalue%20%3FvalueLabel%20%3FEnglish_Wikipedia_article%20%23Show%20data%20in%20this%20order%0A%7B%0A%09%3FWikidata_item_%20wdt%3AP236%20%3Fvalue%20.%20%23Collecting%20all%20items%20which%20have%20P236%20data%2C%20from%20whole%20Wikidata%20item%20pages%0A%09OPTIONAL%20%7B%3FEnglish_Wikipedia_article%20schema%3Aabout%20%3FWikidata_item_%3B%20schema%3AisPartOf%20%3Chttps%3A%2F%2Fen.wikipedia.org%2F%3E%20.%7D%20%23If%20collected%20item%20has%20link%20to%20English%20Wikipedia%2C%20show%20that%0A%09SERVICE%20wikibase%3Alabel%20%7B%20bd%3AserviceParam%20wikibase%3Alanguage%20%22en%22%20%20%7D%20%23Show%20label%20in%20this%20language.%20%22en%22%20is%20English.%20%20%20%0A%7D%0ALIMIT%201000">uses</a>)</li></ul> <ul><li><a href="https://www.issn.org/">ISSN International Centre</a></li> <li><a href="https://portal.issn.org/">ISSN Portal</a></li> <li><a href="https://docs.google.com/spreadsheet/ccc?key=0AusE0e8tdNZVdDFHRnVEZmNCQ3NSNGxNamxDMk44a1E">List of 63800 ISSN numbers and titles</a></li> <li>ISSN InterNational Centre (January 2015), <a href="https://web.archive.org/web/20200712102227/http://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf"><i>ISSN Manual</i></a> (PDF) (2015 ed.), Paris: ISSN InterNational Centre, archived from <a href="https://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf">the original</a> (PDF) on 12 July 2020, retrieved 22 October 2018.</li> <li><a href="https://www.loc.gov/issn/issnbro.html"><i>How U.S. publishers can obtain an ISSN</i></a>, United States: Library of Congress.</li> <li>Canada, Library Archives (8 January 2020), <a href="http://www.bac-lac.gc.ca/eng/services/issn-canada/Pages/issn-canada.aspx"><i>ISSN Canada</i></a>, Ottawa: <a href="/facts/Library_and_Archives_Canada/XDctzIQB">Library and Archives Canada</a>, retrieved 3 April 2020..</li> <li><a href="https://web.archive.org/web/20140715143822/http://www.bl.uk/bibliographic/issn.html"><i>Getting an ISSN in the UK</i></a>, British Library, archived from <a href="https://www.bl.uk/bibliographic/issn.html">the original</a> on 15 July 2014, retrieved 8 October 2008.</li> <li><a href="http://www.bnf.fr/fr/professionnels/s_informer_obtenir_issn/s.obtenir_issn.html?first_Art=non"><i>Getting an ISSN in France</i></a> (in French), Bibliothèque nationale de France, 15 June 2023</li> <li><a href="https://web.archive.org/web/20171211053445/http://www.dnb.de/DE/Wir/Kooperation/ISSN/issnFAQ.html"><i>Getting an ISSN in Germany</i></a> (in German), Deutsche Nationalbibliothek, archived from <a href="http://www.dnb.de/DE/Wir/Kooperation/ISSN/issnFAQ.html">the original</a> on 11 December 2017, retrieved 8 March 2012</li> <li><a href="https://web.archive.org/web/20171224193322/http://www.nlsa.ac.za/index.php/bibsa/isn-agency"><i>Getting an ISSN in South Africa</i></a>, National Library of South Africa, archived from <a href="http://www.nlsa.ac.za/index.php/bibsa/isn-agency">the original</a> on 24 December 2017, retrieved 7 January 2015</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"What is an ISSN?". Paris: ISSN International Centre. Archived from the original on 16 July 2014. Retrieved 13 July 2014. <a href="https://www.issn.org/understanding-the-issn/what-is-an-issn" target="_blank">https://www.issn.org/understanding-the-issn/what-is-an-issn</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Collection Metadata Standards". British Library. Archived from the original on 15 July 2014. Retrieved 14 July 2014. <a href="https://www.bl.uk/bibliographic/issn.html" target="_blank">https://www.bl.uk/bibliographic/issn.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"ISSN, a Standardised Code". Paris: ISSN International Centre. Archived from the original on 16 July 2014. Retrieved 13 July 2014. <a href="https://www.issn.org/understanding-the-issn/standardization" target="_blank">https://www.issn.org/understanding-the-issn/standardization</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>ISSN InterNational Centre. "The ISSN for electronic media". ISSN. Archived from the original on 11 October 2017. Retrieved 3 April 2020. <a href="https://www.issn.org/understanding-the-issn/assignment-rules/the-issn-for-electronic-media/?lang=en" target="_blank">https://www.issn.org/understanding-the-issn/assignment-rules/the-issn-for-electronic-media/?lang=en</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"3". ISSN Manual (PDF). Paris: ISSN International Centre. January 2015. pp. 14, 16, 55–58. Archived from the original (PDF) on 12 July 2020. Retrieved 22 October 2018. HTML version available at www.issn.org Archived 18 October 2018 at the Wayback Machine <a href="https://web.archive.org/web/20200712102227/http://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf" target="_blank">https://web.archive.org/web/20200712102227/http://www.issn.org/wp-content/uploads/2013/09/ISSNManual_ENG2015_23-01-2015.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"What is an ISSN?". Paris: ISSN International Centre. Archived from the original on 16 July 2014. Retrieved 13 July 2014. <a href="https://www.issn.org/understanding-the-issn/what-is-an-issn" target="_blank">https://www.issn.org/understanding-the-issn/what-is-an-issn</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Thren, Slawek Rozenfeld (January 2001). Using The ISSN (International Serial Standard Number) as URN (Uniform Resource Names) within an ISSN-URN Namespace. Network Working Group. doi:10.17487/RFC3044. RFC 3044. Historic. Obsoleted by RFC 8254. <a href="https://datatracker.ietf.org/doc/html/rfc3044" target="_blank">https://datatracker.ietf.org/doc/html/rfc3044</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Online ISSN Validator". Advanced Science Index. Archived from the original on 2 August 2023. Retrieved 16 September 2023. <a href="https://journal-index.org/index.php/issnChecker" target="_blank">https://journal-index.org/index.php/issnChecker</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Identification with the GTIN 13 barcode. ISSN International Centre. Archived from the original on 29 June 2020. <a href="https://www.issn.org/understanding-the-issn/issn-uses/identification-with-the-ean-13-barcode/" target="_blank">https://www.issn.org/understanding-the-issn/issn-uses/identification-with-the-ean-13-barcode/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"Linking ISSN (ISSN-L)". www.nationallibrary.fi. Archived from the original on 26 September 2015. Retrieved 23 December 2018. <a href="https://web.archive.org/web/20150926075657/http://www.nationallibrary.fi/publishers/issn/issnl.html" target="_blank">https://web.archive.org/web/20150926075657/http://www.nationallibrary.fi/publishers/issn/issnl.html</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"Total number of records in the ISSN Register" (PDF). ISSN International Centre. February 2017. Archived (PDF) from the original on 24 February 2017. Retrieved 23 February 2017. <a href="https://www.issn.org/wp-content/uploads/2017/02/Total-records-in-Register.pdf" target="_blank">https://www.issn.org/wp-content/uploads/2017/02/Total-records-in-Register.pdf</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"ISSN for Electronic Serials". U.S. ISSN Center, Library of Congress. 19 February 2010. Archived from the original on 17 February 2014. Retrieved 12 July 2014. <a href="https://www.loc.gov/issn/e-serials.html" target="_blank">https://www.loc.gov/issn/e-serials.html</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"The ISSN-L for publications on multiple media". ISSN International Centre. Archived from the original on 16 July 2014. Retrieved 12 July 2014. <a href="https://www.issn.org/understanding-the-issn/assignment-rules/the-issn-l-for-publications-on-multiple-media/" target="_blank">https://www.issn.org/understanding-the-issn/assignment-rules/the-issn-l-for-publications-on-multiple-media/</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Thren, Slawek Rozenfeld (January 2001). Using The ISSN (International Serial Standard Number) as URN (Uniform Resource Names) within an ISSN-URN Namespace. Network Working Group. doi:10.17487/RFC3044. RFC 3044. Historic. Obsoleted by RFC 8254. <a href="https://datatracker.ietf.org/doc/html/rfc3044" target="_blank">https://datatracker.ietf.org/doc/html/rfc3044</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Powell, Andy; Johnston, Pete; Campbell, Lorna; Barker, Phil (21 June 2006). "Guidelines for using resource identifiers in Dublin Core metadata §4.5 ISSN". Dublin Core Architecture Wiki. Archived from the original on 13 May 2012. <a href="https://web.archive.org/web/20120513221344/http://dublincore.org/architecturewiki/ResourceIdentifierGuidelines" target="_blank">https://web.archive.org/web/20120513221344/http://dublincore.org/architecturewiki/ResourceIdentifierGuidelines</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"MEDLINE/PubMed Data Element (Field) Descriptions". U.S. National Library of Medicine. 7 May 2014. Archived from the original on 27 April 2019. Retrieved 19 July 2014. <a href="https://www.nlm.nih.gov/bsd/mms/medlineelements.html#jid" target="_blank">https://www.nlm.nih.gov/bsd/mms/medlineelements.html#jid</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"The ISSN-L for publications on multiple media". ISSN International Centre. Archived from the original on 16 July 2014. 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