One of the most informative sites on the internet is Medscape. It includes "the Web's largest collection of free, full-text, peer-reviewed clinical medicine articles."
For prescription drug information go to RxList - The Internet Drug Index, or type in the name of the drug below to search RxList. Also below is a medical dicitonary search feature and a medical resource search finder.
If you want to order Medical Text books you can go to Oxford University Press, U.S.A. and look for your topic, then
use the toll free number to call and order. There are many more good sources of information, which are divided into eight categories, listed at top of page.