Question: What is an ISSN, ISBN, DOI or PMID?


Books, Journals, and digital resources are given unique numbers that can be used to identify them and make finding them easier.


E-resources/digital resources

  • DOI (Digital Object Identifier) or a PMID (PubMed Identifier) is a unique number that has been assigned to a digital object, such as an article, book chapter, or data set.

If you have the DOI or PMID for something, it can help you get directly to the content.



  • ISSN stands for International Standard Serial Number. ISSN's have eight digits, and each is unique to a journal publication.



  • ISBN stands for International Standard Book Number. ISBN's have 10 or 13 digits, and each is unique to a book publication.




Answered By: NYU Reference Librarians
Last Updated: Jul 26, 2019Views:

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