The big one that left a lasting impression for me at an early age was Lew Hunter's Screenwriting 434. It does a very good job illustrating a lot of the technical mechanics of the format and the Hollywood guidelines and expectations that have built up around it (including the page per minute expectation, and even the expectations on page per act, which is another formula that Hollywood has), and some of why, using an example screenplay throughout.

(Just be forewarned it is not a great example screenplay in the usual fashion of such teaching examples because it is designed more towards the lesson plan than coherency/quality as a story of its own; and also arguably another example of that old weird maxim "those who can't, teach" given Lew Hunter's mostly TV Movie writer IMDB credits.)