PubMed This link opens in a new windowPubMed comprises more than 28 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites. PubMed is maintained by U.S. National Institutes of Health's National Library of Medicine (NIH/NLM) and is freely accessible to all Web users.