Currently reading These Are the Voyages…..TOS season 1 by Marc Cushman. The first in a three volume series about the making of Star Trek, the original series, with each volume consisting of one season of the show. Not only is it a very in-depth (and well researched) look at how the show was made, but also how TV shows were made in the 60’s in general. Backstories are given for all of the actors on the show, as well as any principal crew (writers, directors, producers, and so on), and then each episode is broken down by how the script was written, the necessary pre-production, and what scenes were filmed on which day. Lots of interesting tidbits. I have never read any of the other books published about the behind the scenes stuff from Star Trek, but from what I have heard this three volume series is about as definitive as it gets.