PubMed is a search system from the National Library of Medicine. It includes references from MEDLINE and MEDLINE in Process, as well as a small number of references not included in these databases. It features built-in search filters for diagnosis, therapy, and prognosis, and includes links to databanks of DNA/protein sequence and 3-D structure data. PubMed also links to publishers’ sites for full-text journals, although many of these journals require subscriptions for viewing. Older records (1950-1965) formerly in OLDMEDLINE have also been added to PubMed.