I learned about the book
Teaching the Dog to Think, by Kimberly Davis, from a post at
Chronicles of a Puppy Walker. It was many things that I'm interested in: a book about dog training, a book about "thinking dog" training, and free. For the Kindle, anyway. Not that I have a Kindle, but they have an application for every platform. So, I went to Amazon, downloaded the app, downloaded the book, and blitzed right through it.
Davis starts out the book with her first night going to agility class with her rough collie, Willow. Willow is a young, exuberant dog, and he frequently has problems with being nutso and pulling on the leash, so he wears both a flat buckle collar and also a choke chain.