Some papers have the Digital Object Identifier (DOI) which uniquely identify them, some other have an oai identifier (e.g. oai:arXiv.org:1402.3722). Even though I inspected the metadata of different sources like core, microsoft academic, and semantic scholar I couldn't find a unique identifier which is used among all sources of research papers.

How are all scientific publications uniquely identified?

  • Are you looking for unique identification by authors, publishing houses, librarians or the world?
    – origimbo
    Commented Oct 23, 2018 at 8:09
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    What makes you think such unique identifiers exist?
    – Thomas
    Commented Oct 23, 2018 at 8:46
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    I suggest revising (in the title and body) "How are all scientific publications uniquely identified ?" to "Are all scientific publications uniquely identifiable?" or "Is there a system to uniquely identify all scientific publications?"
    – user2768
    Commented Oct 23, 2018 at 8:58
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    "How are all scientific publications uniquely identified?" For citation usually by a combination of (title, journal, issue, pages, year, authors, doi, ...). Commented Oct 23, 2018 at 12:06
  • CORE and SemanticScholar definitely use DOIs, what do you mean that they don't?
    – Nemo
    Commented Oct 23, 2018 at 14:06

3 Answers 3


Research publications predate the digital age, so only a fraction has a digital identifier. The unique identifier traditionally used is the full citation, of which various formats exist to suit discipline-specific needs. It is very likely for a full citation to be unique.

(However, automatic data analysis may not be able to recognize the identity of diffently formated citations of the same publication. That's DOI's strong suit.)

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    I’m not sure I agree with the reasoning: books predate the digital age, yet even those books (up to a point) all have digital identifiers (ISBN for most of them, and other — albeit not uniform — identifiers for older works). Likewise, older publications can be (and are) digitally archived and identified in retrospect. Commented Oct 23, 2018 at 13:38
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    @KonradRudolph First, I think there's an overloading of the word "digital" here. ISBNs were introduced as an ISO standard in 1970, and while they (and other serial numbers) consist of a series of digits (one meaning of 'digital'), this was certainly before the "digital age". Second, I agree with you. I also don't see any particular reason why a DOI-like number for research papers couldn't have been introduced way before 2000, say in the early 1900s. There probably wasn't much need for it, but it could, in principle, have been done.
    – Anyon
    Commented Oct 23, 2018 at 14:04
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    @Anyon, Konrad Rudolph, you're both correct, but the need for unique IDs presumably is a result of digitization in the sense of computerization, since computers don't deal well with the ambiguity of traditional citations. Commented Oct 23, 2018 at 14:52
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    I think the key piece of this answer is the parenthetical at the end: the unique IDs aren't for "us", they are for our digital underlings and future overlords to prevent them from making mistakes. All of the other citation stuff is for "us" and is sufficiently unique going back a long time.
    – Bryan Krause
    Commented Oct 23, 2018 at 15:55
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    @Trilarion The problem is, by definition, hashes completely change in cases where the actual content has not. When PDF becomes obsolete and papers get converted into whatever new format, you'll get a change... Some publishers put a cover page on papers with an ad, or they watermark the paper with the downloading IP, also causing changes. DOIs don't have this issue by not assuming binary representations = content.
    – user71659
    Commented Oct 25, 2018 at 0:15

I work at Crossref and we run a registry of DOIs with attached metadata beyond such as funder acknowledgements, whether it's been retracted, etc. Our DOIs (about 100 million) are specifically citation identifiers and also persistent links. DOI is also the ISO standard for identifying research publications. 11,000 publishers use Crossref but yes they have not all gone back to their print archives to digitise them and assign DOIs yet, books especially are lagging behind. It integrates with DataCite DOIs for data and software citations (about 10 million of them), and with ORCID iDs which identify authors & contributors (about 5 million so far). There is also ROR.community starting up to uniquely identify research institutions. All these are open community-governed nonprofit organizations. ArXiv is pretty much the only publisher that doesn't (yet) use DOIs. Centre for Open Science does for all the other 'Xivs', as does BioRxiV etc.

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    Of course papers on the arXiv are "published" in a loose sense of the word ("made public"), but at the moment a DOI usually seems to indicate that a paper is published in a stricter sense (e.g. published in a peer-reviewed journal)...?
    – Earthliŋ
    Commented Oct 23, 2018 at 14:41
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    @Earthliŋ It's worth noting your example is neither necessary, nor sufficient, since multiple organisations will issue a DOI for non-peer reviewed papers (or non-papers) and there are journals offering 'peer-review' (in small fields, sometimes legitimately) which aren't authorised issuers of DOIs.
    – origimbo
    Commented Oct 24, 2018 at 8:24
  • Hi @Earthliŋ, there are millions of DOIs for lots of non-peer-reviewed and less 'strict' stuff, e.g. preprints, theses, reports, working papers, diagrams, component figures and charts, software, blog posts, peer review reports, even annotations/comments. Basically anything citeable.
    – ynnig
    Commented Oct 26, 2018 at 9:24

How are all scientific publications uniquely identified ?

Formally, they aren't: There is no system to uniquely identify publications. But, author(s), year of publication, and title are typically sufficient to uniquely identify publications, because authors typically publish different works with different titles and it is unlikely that distinct author(s) with the same name(s) will publish in the same year with the same title. Moreover, it is even more unlikely once publication venue is added and distinct once page numbers are added (assuming no two publication venues share the same name in the same year). So, a full citation should suffice to uniquely identify publications, but there may exist (with low probability) publications that cannot be uniquely identified.

(Uniquely identifying authors of a publication is more problematic.)

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    "Moreover, it is even more unlikely once publication venue is added and distinct once page numbers are added." Including the page numbers should make it impossible to not uniquely identify the publication for all practical purposes. Commented Oct 23, 2018 at 12:11
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    @Trilarion That's why I wrote "and distinct once page numbers are added". Actually, thinking about it, that's not strictly true. Two publication venues might share the same name.
    – user2768
    Commented Oct 23, 2018 at 12:44

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