Reddit mentions of Theatre Sound (Theatre Arts (Routledge Paperback))

For engineering concepts, and a great general reference on sound systems and how they work, the Yamaha Sound Reinforcement Handbook

For sound system design, the best reference is Bob McCarthy's Sound Systems: Design and Optimization

For another great book that discusses both system design as well as artistic sound design, John Leondard's Theatre Sound is top notch.

Shannon Slaton's Mixing a Musical: Broadway Theatrical Sound Techniques is a great picture of how the "big shows" are run.

For a beginner's guide to sound, the [http://www.soundcraft.com/support/gtm_booklet.aspx](Soundcraft Guide to Mixing) is a good primer: not as technically dense as the Yamaha book.

There are others out there, these are my favorite.