I too pretty much agree with most of the other posters. However, riding with “correct” contact is a dressage concept, and while books can be helpful, you might do better to find a really good dressage basics instructor. For example, a well trained dressage horse does not just stretch to the bit, they actually stretch to the bit at whatever length of rein they are given, and put enough tension on the bit to take the reins through the rider’s open hands. The rider determines the length of rein by opening or closing the fingers — opening the fingers allows the horse to gently pull the reins through the rider’s hands (emphasis on GENTLY), while closed fingers tell the horse when he has gone down far enough, and the horse must also follow the bit back up. My issue with books is that one must understand the principles being discussed, and this can often be a case of 1 picture being worth a thousand words, or on good demonstration of what should be happening and what it feels like can be worth 20 thousand words. Some of the dressage concepts are simply so radically different from what is often taught in the US as basic good riding is the opposite of top quality dressage, and this makes these concepts hard to understand from just a book.