Template:Citation Style documentation/id2

The following identifiers create links and are designed to accept a single value. Using multiple values or other text will break the link and/or invalidate the identifier. In general, the parameters should include only the variable part of the identifier, e.g. |rfc=822 or |pmc=345678.

arxiv: arXiv identifier; for example: |arxiv=hep-th/9205027 (before April 2007) or |arxiv=0706.0001 (April 2007 – December 2014) or |arxiv=1501.00001 (since January 2015). Do not include extraneous file extensions like ".pdf" or ".html". Aliases: eprint.
asin: Amazon Standard Identification Number; if first character of asin value is a digit, use isbn. Because this link favours one specific distributor, include it only if standard identifiers are not available. Example |asin=B00005N5PF. Aliases: ASIN.
- asin-tld: ASIN top-level domain for Amazon sites other than the US; valid values: {{#lst:Help:CS1 errors|asin-tld_values_list}}. Aliases: none.
bibcode: bibcode; used by a number of astronomical data systems; for example: 1974AJ.....79..819H. Aliases: none.
biorxiv: bioRxiv id, as in the entire DOI (e.g. 10.1101/078733 for http://biorxiv.org/content/early/2016/10/01/078733 or https://doi.org/10.1101/078733; 10.1101/2020.07.24.220400 for https://doi.org/10.1101/2020.07.24.220400). Aliases: none.
citeseerx: CiteSeerX id, a string of digits and dots found in a CiteSeerX URL (e.g. 10.1.1.176.341 for http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.176.341). Aliases: none.
doi: Digital object identifier; for example: 10.1038/news070508-7. It is checked to ensure it begins with (10.). Aliases: DOI.
- Supports accept-this-as-written markup to indicate valid DOIs using a non-standard format, see below.
- doi-broken-date: Date a valid DOI was found to be non-working/inactive at https://doi.org. Use the same format as other dates in the article. Aliases: none.
eissn: International Standard Serial Number for the electronic media of a serial publication; eight characters may be split into two groups of four using a hyphen, but not an en dash or a space; example |eissn=1557-2986. Aliases: EISSN.
- Supports accept-this-as-written markup to indicate valid eISSNs using a non-standard format, see below.
hdl: Handle System identifier for digital objects and other resources on the Internet; example |hdl=20.1000/100. Aliases: HDL.
isbn: International Standard Book Number; for example: 978-0-8126-9593-9. Hyphens in the ISBN are optional, but preferred. Use the ISBN actually printed on or in the book. Use the 13-digit ISBN – beginning with 978 or 979 – when it is available. If only a 10-digit ISBN is printed on or in the book, use it. ISBNs can be found on the page with the publisher's information – usually the back of the title page – or beneath the barcode as a number beginning with 978 or 979 (barcodes beginning with any other numbers are not ISBNs). For sources with the older 9-digit SBN system, use sbn. Do not convert a 10-digit ISBN to 13-digit by just adding the 978 prefix; the last digit is a calculated check digit and just making changes to the numbers will make the ISBN invalid. This parameter should hold only the ISBN without any additional characters. It is checked for length, invalid characters – anything other than numbers, spaces, and hyphens, with "X" permitted as the last character in a 10-digit ISBN – and the proper check digit. Aliases: ISBN.
Supports accept-this-as-written markup to indicate valid ISBNs using a non-standard format, see below.
ismn: International Standard Music Number; for example: 979-0-9016791-7-7. Hyphens or spaces in the ISMN are optional. Use the ISMN actually printed on or in the work. This parameter should hold only the ISMN without any additional characters. It is checked for length, invalid characters – anything other than numbers, spaces, and hyphens – and the proper check digit. Aliases: ISMN.
issn: International Standard Serial Number; eight characters may be split into two groups of four using a hyphen, but not an en dash or a space; example |issn=2049-3630. Aliases: ISSN.
- Supports accept-this-as-written markup to indicate valid ISSNs using a non-standard format, see below.
jfm: Jahrbuch über die Fortschritte der Mathematik; do not include "JFM" in the value; example |jfm=53.0144.01. Aliases: JFM.
jstor: JSTOR reference number; for example: |jstor=3793107. Aliases: JSTOR.
lccn: Library of Congress Control Number. When present, alphabetic prefix characters are to be lower case and without a space; example |lccn=79-57364 or |lccn=2004042477 or |lccn=e09001178. Aliases: LCCN.
mr: Mathematical Reviews; example |mr=630583. Aliases: MR.
oclc: OCLC Number for looking up publications in the WorldCat union catalog; example |oclc=9355469. Aliases: OCLC.
ol: Open Library identifier; do not include "OL" in the value; example |ol=7030731M. Aliases: OL.
osti: Office of Scientific and Technical Information; example |osti=4367507. Aliases: OSTI.
pmc: PubMed Central; use article number for open repository full-text of a journal article, e.g. |pmc=345678. Do not include "PMC" in the value. . Aliases: PMC.
pmc-embargo-date: Date that pmc goes live; if this date is in the future, then pmc is not linked until that date. Aliases: none.
pmid: PubMed; use unique identifier; example |pmid=17322060 Aliases: PMID.
rfc: Request for Comments; example |rfc=3143. Aliases: RFC.
sbn: Standard Book Number; example |sbn=356-02201-3. Aliases: SBN.
- Supports accept-this-as-written markup to indicate valid SBNs using a non-standard format, see below.
ssrn: Social Science Research Network; example |ssrn=1900856. Aliases: SSRN.
s2cid: Semantic Scholar corpus ID; example |s2cid=37220927. Aliases: S2CID.
zbl: Zentralblatt MATH; example |zbl=0472.53010 For zbMATH search results like JFM 35.0387.02 use |jfm=35.0387.02. Aliases: ZBL.

In very rare cases, valid identifiers (f.e., as actually printed on publications) do not follow their defined standard format or use non-conforming checksums, which would typically cause an error message to be shown. Do not alter them to match a different checksum. In order to suppress the error message, some identifiers (|doi=, |eissn=, |isbn=, |issn=, and |sbn=) support a special accept-this-as-written markup which can be applied to disable the error-checking (as |<param>=((<value>))). If the problem is down to a mere typographical error in a third-party source, correct the identifier value instead of overriding the error message.

For some identifiers, it is possible to specify the access status using the corresponding |<param>-access= parameter.

For {{cite journal}}, some identifiers (specifying free resources) will automatically be linked to the title when |url= and |title-link= are not used to specify a different link target. This behaviour can be overridden by one out of a number of special keywords for |title-link= to manually select a specific source (|title-link=pmc or |title-link=doi) for auto-linking or to disable the feature (|title-link=none).

It is not necessary to specify a URL to a link identical to a link also produced by an identifier. The |url= parameter (or |title-link=) can then be used for providing a direct deep link to the corresponding document or a convenience link to a resource that would not otherwise be obviously accessible.