dressage by henry wynmalen, he started the dressage competition thing in england, his books are very readable, he must have been a great bloke, a and c black are the publishers i think, he was also involved in the start of combined training and horse trials in cluding badminton, there is a biographical section about his life, he also wrote horse breeding and stud management, one of my favourite books, and although a bit outdated still a sort of bible on the subject
Not a real history one, but Tug of War - Classical vs. Modern dressage by Gerd Haussman (?), is very very good! Got it 6 days ago and I've read it twice now.
What are you looking for specifically? A historical/academic overview similar to the one you cited? More technical/instructional writings representative of the various Schools?
These are great suggestions, thank you! I'd heard of Wynmalen and Haussman and that Great European Schools book looks beautiful.
As to what I'm looking for I have a broad remit. I suspect there won't be many academic-y books like the one I linked to (which is great and tells you a lot about the development of ideas of nation and how riding styles were linked to that). I'm especially interested in James Fillis, but I think I may be able to find scans of things he wrote on Archive.org. There's also a book on écuyers which I'm desperate to read, but I think will be hard to track down.
go to www.classicalridingclub.co.uk i think there is info about books you are looking for if not ask them, i know sylvia loch has great knowledge of such books