An excellent training resource for aggressive dogs, Parsons made the switch from traditional punishment-based training after various "professional" trainers' attempts to "correct" her aggressive dog resulted in a worsening and deeper ingraining of the aggressive behavior.
Click To Calm discusses differences between positive and punishment based training methods, and the positive methods she used to help her dog overcome his aggression.
Primarily focused on the "Look-At-That" technique, where the handler clicks and rewards the dog for looking at his or her trigger from a safe distance, below threshold, this book is designed to reduce your dog's emotional response to triggers through systematic-desensitization and counter-conditioning.
This book is very thorough, and broken down into simple and easy to follow segments, making it extremely user-friendly. It relies on pre-planned "set-ups", where there must be a stationary decoy or trigger, so you will have to have a helper or willing partner to practice (I use strangers at the park- they usually have no intention of interacting with my dog and pretend not to mind that I'm following them around with an insane dog :)
I have used this technique with some success with my aggressive rescue dog, but find it is not practical in the "real world" i.e., walks etc. Highly recommend this book in conjunction with Behavior Adjustment Training by Grisha Stewart, and Control Unleashed by Leslie McDevitt.