I love Cherry Hill's How to Think Like a Horse. Anything by Cherry Hill is worth a read, lol. I also have a book called Trail Riding, I think written by Rhonda Hart Poe. Everything you'd ever want to know about trail riding and everything involved. Some of the training tips for major behavioral issues sound a little "iffy" to me, but there is wonderful info on trail safety, correct packhorse loading, conditioning, and more.
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown