General Books
If you are starting out or never took the time to consider the history of riding, "The Story of Riding" is a great book to give you a historical context for the evolution of riding and training horses.
E.M. Kellock “The Story of Riding”
Cherry Hill “101 Arena Exercises”
Dr. Deb Bennett “Lessons from Woody: Teaching Your Horse to Carry Himself Straight”/ “The Birdie Book”/ “Principles of Conformation Volumes 1-3”
Gerd Heuschmann “Tug of War: Classical vs. Modern Dressage”
Susan Harris “Horse Gaits, Balance, and Movement”