[.ca] Spacecraft Attitude Determination and Control (ISBN 9027712042)

Most authoritative and rigorous treatment of ACS I've seen.:
Provides the only text I have seen on quaternion math and its relation to more traditional attitude matrices and Euler dynamics. The presentation allows algorithm generation without too much fuss, and it is rigorous but not to a fault. Definitely graduate level reference material for practicing ACS engineers. I have found it indispensable.

*The* authoritative text on the subject:
This book is intended for technical professionals, who want an exhaustive mathematical and geometric reference to the techniques of spacecraft attitude determination and attitude control. Although the book is a little old, the principles are still relevant, and there is simply no other comparable compilation.