MEDLINE is the authoritative bibliographic database of The National Library of Medicine, delivering comprehensive scientific records to articles in the life and biomedical sciences. The coverage of material is extensive and international in scope.

PubMed Central is an open-access digital archive of full-text journals in the biomedical and life sciences from the US National Institutes of Health (NIH). Free and unrestricted access to biomedical literature is the objective of the database.

Some journals may delay release of their full-text issues in the database for a certain period of time after publication.