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DOI vs PMID vs ISBN: when to use which
Identifiers are the fastest path to reliable citations. If you can include a stable identifier, you reduce ambiguity and make it easier for readers (and tools) to verify the reference.
DOI (Digital Object Identifier)
DOI is the most broadly useful identifier for scholarly articles, conference papers, and many datasets.
- Use DOI when available for journal articles.
- Prefer the canonical form (e.g.,
10.xxxx/xxxxx) and let tooling normalize URLs. - Watch for typos: a single character can resolve to a different paper.
PMID (PubMed ID)
PMID is a strong identifier for biomedical literature indexed by PubMed.
- Use PMID when DOI is missing or when you’re working in a PubMed-first workflow.
- Some records map to DOI; others don’t—don’t assume both exist.
ISBN (books)
ISBN is for books, but it’s easy to cite the wrong edition.
- Verify edition, publisher, and year—different editions can have different ISBNs.
- Translations and regional printings can have different ISBNs.
- A correct ISBN does not guarantee the page number you cite exists in that edition.
What to do when you only have a URL
Publisher URLs are helpful but can be unstable. They also sometimes redirect or hide metadata behind scripts. Use them as a starting point and try to recover a DOI/PMID/ISBN where possible.
Quick workflow
- Collect identifiers (DOI/PMID/ISBN) where possible.
- Run a batch check in Citation Verification.
- Generate formatted citations with Citation Generator.
- Spot-check the most important items against the publisher record.