Medline Resource
PubMed	http://www.ncbi.nlm.nih.gov/pubmed/
Internet Grateful Med	http://igm.nlm.nih.gov/
Avicenna	http://www.avicenna.com/
BioMedNet	http://www.biomednet.com/
HealthGate	http://healthgate.com/
Medical Matrix	http://www.medicalmatrix.com/
Medscape	http://www.medscape.com/
Infotrieve	http://infotrieve.com/