The books below are all reference resources you should find helpful, but bear in mind that there's no such thing as a definitive work in this arena. Robert McKee's book, for instance, is pretty much accepted as the industry standard on screenplay structure, but many people find the style a little too grand for its own good, coming as it does from a man who has never in his life written a successful screenplay. Moreover, it advocates a standardised structure, a recipe for formulaic movie-writing. It's useful for grasping the terminology – most executives will have read it, or at least have had someone read it for them – so it's as well to be aware of it. It contains oodles of helpful insights, but I'm not convinced it's a terrific aid to creativity. Don't take it, or any of the other books, as gospel. They're aids. That's all.