I have studing the genetics side of breeding and wow. It is hard to understand unless you read into it. You must read everything 3 times before you understand at least for me. There is site but I don't know address. It sort of supported by the UKC, I think. google, the pitbull network. It is a great start to understanding genetics, and yes you have no understanding of breeding until you read this. It has open my eyes up to a new style of breeding in electronic age. It defintely will help produce better puppies for you and better image(understanding) of a true APBT. The man who did all the writing is a avid pitbull breeders and has a Phd. in genetics who better to explain genetics. He uses analogies that contain things we care about and not a bunch of mobogumbo crap. It is one best things I have read about breeding. Worth it's weight in gold I swear. Google pitbull network.