We are fortuanate enough to have obtained a few copies of Harry Boldt's English Translation of 'The Dressage Horse' Chapter III. This book is does a fantastic job of describing and diagramming the aids like no other book. It is out of print and these are some of the only remaining copies. You can order your own copy at http://www.xenophonpress.com/ while they last. They are very difficult to find and an incredible resource to have at your finger tips.