Like Doc E said Wolter's books are very outdated. Even when they were first written, Wolters wasn't an accomplished trainer. Often Wolter's books will lead you to a dead end wondering what do I do now when the dog doesn't respond as he states they will.The better materials out there are mostly based on Rex Carr's teaching and have evolved from him. Flow charts, Force-Fetch, Collar-Conditioning are just a few.