This link will take
you to several free e-articles on various training and behavioral
issues-including one that helps with introduction of a dog into a home with a
cat- and many other great articles!
http://leerburg.com/dogtrainingebooks.htm
This link goes to a
nice German Shepherd info site with training techniques that will work for all
dogs, but specifically work well for the GSD and related breeds.
http://www.germanshepherd-breed.org/training-articles/