As a relative beginner, I was recommended and bought a couple of books. Horenstein's book was good, if a little basic - would make a great book for a first photography class - a little too much on the camera side of things for me. I found Vestal's 2 books to be a little more geared towards darkroom matters and got the the most out of them. They are a little outdated in some respects, but he explains the basic process, gives a couple nice tips, and also shows the way for testing methodology if you choose to go down that road. You can get them off of Amazon used for a couple bucks. Tom Grimm's book was decent too.