Both these books about horses are interesting and informative:
Hollywood Hoofbeats: The Fascinating Story of Horses in Movies and Television


by Petrine Day Mitchum (daughter of Robert Mitchum) and Audrey Pavia, available from Amazon. com, paperback also Kindle version
The horses that captured the moviegoers’ hearts are the common denominator in Hollywood Hoofbeats. As author Petrine Day Mitchum writes, “the movies as we know them would be vastly different without horses. There would be no Westerns—no cowboy named John Wayne—no Gone with the Wind, no Ben Hur, no Dances with Wolves…”

Understanding Harness— Balanced Draft, Breast Collars, Neck Collars
by Barb Lee, available from CAA website/bookstore 

Understanding Harness by harness maker Barb Lee This is a great booklet for both beginning and advanced carriage drivers on understanding the carriage driving harness. You will learn mechanics of neck collar and breast collar harness as well as an understanding of balanced draft.