There's this one screenwriter, William Goldman. I was first introduced to his work when a good friend insisted on reading aloud to a group of our friends a particular scene from a book that he'd found. I was shocked to realize later when I was watching The Princess Bride that I already knew the scene atop the Cliffs of Insanity; yes, it was that same scene.
I later read the book myself and enjoyed it...but that's not what I'm dealing with here. Yesterday, I finished reading his book Adventures in the Screen Trade: A Personal View of Hollywood and Screenwriting which I found to be an excellent discussion of the movie system. The book is a little old now (written in 1983), but there's still a lot of gold in it. If you have an interest in what The Industry is like, I think this is worth a read.
A few hours later, I also finished reading Osprey Warrior #71: Roman Legionary 58 BC – AD 69, which deals with the troops of the Republic during into the troops of the Empire. It's a pretty well put together book. If you're interested in the period, it might be a good choice for some concentrated data.