Spike! is the story of the 1984 USA men's olympic volleyball team as told by its head coach Doug Beal. It's definitely an interesting read.
My Profession - The Game is the English translation of the last of several books written by legendary Russian volleyball coach Vyacheslav Platonov
Although there are a few interesting elements and worthwhile anecdotes, overall this is not a volleyball coaching book I am inclined to recommend for reading.
Winning Volleyball is a book of its time in that is doesn't reflect the modern game in many respects, but it's not without value to current volleyball coaches.
Volleyball Skills & Drills is a book by the American Volleyball Coaches Association featuring ten chapters on various aspects of coaching.
As it's title suggests Coaching Volleyball Technical and Tactical Skills is a book focused on teaching the technical skills and tactical aspects of volleyball.
Here's my review of the book Incredible Volleyball Lead-Up Games and Drills, which has some potentially useful features for volleyball coaches.
Thinking Volleyball by Mike Hebert will make you think about your volleyball coaching, not just present you with a bunch of drills and training techniques.