Advanced Schutzhund, by Ivan Balabanov and Karen Duet takes a problem-solving approach to Level III work that will help competitors bring their dogs to the highest level of their ability.
Tracking, obedience, and protection are dealt with individually, analyzing specific problems that crop up in each skill and offering step-by-step solutions. Some of the techniques are better explained in the video series (see below) because the trainer is able to see it done, but the book explains in detail "how to" and "why."