This might be an oldie, but it's a goodie - all still relevant and the exercises described can easily be adapted. It's a shame that Cavaletti themselves have fallen out of favour - raised poles just don't have the same sturdiness and I miss the set we had when I was a child. Maybe they deserve a comeback!
Since Reiner and Ingrid Klimke are my big equestrian heros, I just love their books. Whenever I'm stuck, they know how to help me.
In easy steps, this book show's great ways to school your horse and yourself in walk, trot and canter, while riding and lunging with a lot fun and variety. Because often, the small things make the big difference.