DermIS.net is the largest dermatology information service available on the internet. It offers elaborate image atlases (DOIA and PeDOIA) complete with diagnoses and differential diagnoses, case reports and additional information on almost all skin diseases
DermNet NZ was founded 22 years ago by a group of Dermatologists from New Zealand. It has become a world-renowned resource of skin disease information.
Fitzpatrick's Dermatology, Ninth Edition, 2-Volume Set by 
