Where can I find credible (and easy to acess) medical information about what is !

Where can I find credible (and easy to acess) medical information about what is a disease and what is not?

I'm doing a research paper and my thesis is to say that alcoholism is not a disease (BUT PLEASE, this is not my question...I already have my arguments and you won't change my mind...besides, I'm almost done with the paper, and I cant change it now, hihihi).
I'd like to have reliable information saying if obesity, eating disorders, nynphomania, pathologic gambling, and other addictions are diseases.
Anyone knows where?

4 weeks ago
Oh thank you all!
And yes..I will learn how to spell, don't worry..I've been studying English for only one year...so I'll be fine =D
(besides, I think spelling was not my only problem, you should have noticed that I'm not a english native speaker...)

I do my research on Webmd.com or mayoclinic.com

Also the Nat'l Institute of Health

Good luck!