• www.ncbi.nlm.nih.gov

PubMed, one of the largest medical databases in the world, is a joint institution of the US National Center for Biotechnology Information NCBI, National Library of Medicine NLM, the National Institutes of Health NIH and the American government.
In this database, more than 11 million publications and study results from Medicine (MEDLINE, PREMEDLINE) and from related subject areas are covered.
Access is free.