Der Schuthund by Helmut Raiser
Schutzhund Obedience Training in Drive by Dildei & Booth
The GSD, History, Development, Genetics by MB Willis
and of course I have a copy of Susan Barwigs' book
Fireside Book of Dog Stories (favorite fiction)
I have more, but these seem to be the ones I go to the most.
I also have saved many good USA magazine articles (in the old days they had some really good articles, I think they are starting to do that again). I have also kept many articles from hunters, etc. because even though they are not speaking directly to my breed or goal, they still have many good methods that cross over to what I do.
That being said, I subscribe to no ones specific methods because all dogs are different, & no matter how well spelled out, each author is subject to interpretation! The books do provide a little foundation as well as tips when you find yourself in a sticky spot. :lol:
There is no substitute for finding a good club or teacher when it comes to our kinds of dogs.