I have to say that ive learned this hobby from 3 things..This forum, ED Rosenthal's Marijuana growers handbook, and a good friend of mine from here.
This book is really good and told me a lot of things wich is not always can be found on the internet easily.
In my opinion if you wanna be an expert grower and wanna do good quality near decent yield you should buy Ed Rosenthal's book. There are several books from him i prefer Mj growers handbook.