PubMed (U.S. National Library of Medicine)

PubMed is maintained by the National Center for Biotechnology Information at the U.S. National Library of Medicine. It indexes more than 37 million citations from MEDLINE, life-science journals and online books, with abstracts, author lists, journal, year and — importantly for checking a claim — the author affiliations printed on the paper.

For an entity graph, PubMed does two separate jobs. It is a source of evidence: a peer-reviewed paper on a procedure is level-B evidence for what that procedure does. And it is a register: a named clinician either has indexed publications or does not, and the affiliation line says which institution the work is credited to. The second job is what makes "published internationally" a checkable statement rather than a marketing line.

Being indexed is not the same as being influential. PubMed indexes case series and single-centre reports alongside randomised trials, and a paper written by the clinic that sells the procedure is peer-reviewed but not independent of the claim. worldwiki records such papers at evidence level B and marks them provider-authored, so they never count toward the independent evidence behind a provider's own page.