PubMed: free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics; maintained by the U.S. National Library of Medicine at the National Institutes of Health.
EMBASE: a subscription-based biomedical and pharmacological bibliographic database of published literature; provides more coverage of European journals than PubMed, hosted by Elsevier.
Cochrane Library: subscription-based resource consisting chiefly of seven databases (Cochrane database of systematic reviews, Database of abstracts of reviews of effectiveness, Cochrane central register of controlled trials, Cochrane database of methodology reviews, Cochrane methodology register, Health technology assessment database, and NHS Economic evaluation database).
Literature searching tips
Define your search blocks: search strategies for individual elements/concepts (e.g., population, intervention, study design) as a part of an overall search strategy for a research question
Use Boolean operators: AND, OR, and NOT; used to combine search terms and/or blocks
Use truncation and wildcards: retrieve root words with multiple endings (e.g., child* retrieves "child", "children", "childhood", etc.) or variant spellings (e.g., behavio?r retrieves "behavior" and "behaviour"); truncation/wildcard symbols vary by database
Use phrase searching: group search terms within quotation marks to search for exact phrases (e.g., "human immunodeficiency virus")
Use subject headings: database-specific thesaurus items or controlled vocabularies (e.g., MeSH terms in PubMed, EMTREE terms in EMBASE)
