If you're interested in dog psychology, I highly recommend The Other End of the Leash and For the Love of A Dog by Patricia McConnell. She has a lot of insightful advice on dog behavior. Some of it may seem like common sense to experienced dog handlers, yet there is also a lot of information I wasn''t aware of that really helps put things in focus. She discusses 'thin slicing' which is a milisecond of a dog's posture that can signal so much to come... a really engaging read. Check it out!