I apologize for the delay in responding, and thank you for posting. Some books directors return to again and again are Film Directing Shot by Shot by Steven Katz, Directing Actors by Judith Weston, and On Directing Film by David Mamet. Many libraries lend them as e-books through apps like Libby. You can also learn a great deal from directors' commentaries and interviews, and from our directing articles on StudentFilmmakers.com. Which kind of directing are you most interested in?