Books
The Photographer's Guide to Posing
by Lindsay Adler (2014 - 448 pages)
This book took me a little by surprise. From the first chapter it goes very in depth into not only diagram for posing as some other books does, but goes deeper into how focal lengths, angle, distance, etc. affect the subject being photographed.
So far, I feel like this book isn't a book that just show you images for you to start using in your photography. It train you to see why certain things work and why certain thing doesn't. Having this fundamentals will make it easier to not only follow diagrams from other books, but also quickly see mistakes or other what subtle changes that is needed for a composition to work.