National Center for Biotechnology Information (NCBI) PubMed Strengths  Provides access to the biomedical journal literature, including over 22 million citations from the mid-1960 s to the present  Controlled vocabulary (MeSH) helps to focus your search  Provides links to full-text electronic articles  Updated daily  Related Articles feature uses a word-weighted algorithm to link from a particular citation to additional relevant material Weaknesses  Can be time-consuming to search because of its size  Quick searches may omit relevant citations, with the danger that you may miss important viewpoints in the literature  Controlled vocabulary terms (MeSH) are updated annually, so may not accommodate new concepts well  Includes literature from over 70 countries, but has a North American bias and may omit relevant European literature