Resources for learning about amplifiers?

Wondering what resources people would recommend for learning about amplifiers. There are the obvious websites (Wikipedia is always a good start) and probably some obvious books (maybe some of Dave Hunter's books?) but I figured it couldn't hurt to ask the question and see if there was some consensus about what resources are especially worthwhile. If I were to level set I would say that I'm looking for good 101, maybe even 201, course level material. Thanks!