Beyond the Basics: Unlock Your Dog's Behavior by Denise Fenzi is a great book. The book explores a dog's temperament, emotions, and health and the role these factors play in training.
Decoding Your Dog: Explaining Common Dog Behaviors and How to Prevent or Change Unwanted Ones is also an excellent choice. The authors of this book are all veterinary behaviorists. The book explains why dogs act the way they do and how you can effectively shape your dog's behavior. Not only are common problems addressed in this book but so are compulsive behaviors and separation anxiety.
I hope these suggestions are helpful.