Incidentally, I pulled down this list of recommended ballroom syllabus technique books from dancesport.uk.com Tid-bits newsletter. Looks like a good place to start.
Books for Ballroom Dancing:
1."Ballroom Technique," ISTD, is the book that everyone must have. It is meant for Teachers but I don't know why a keen student shouldn't get one. All 4 ballroom dances, Waltz, Slow Foxtrot , Quickstep and Tango are covered from Bronze to Gold level syllabus figures.
2. "Ballroom Dancing by Alex Moore" is a wonderful, easy to read book on Ballroom dances and it even has foot patterns for man and lady. There is Viennese Waltz and a lot of other information in it also. Actually the Ballroom Technique and this Ballroom Dancing by Alex Moore go hand in hand, I say get both.
3. "Technique of Ballroom Dancing" by Guy Howard. I think this book has been adopted by IDTA. This is a wonderful book similar to ISTD book. The introductory pages are more detailed and everything good has to be said about the book.
Latin Books:
1. The ISTD "Revised Technique of Latin American Dancing" is no longer published. Try to find a vendor who might have some old copies left. I think this book has all 5 Latin Dances well covered. The 5 new ISTD manuals are replacing the ISTD technique book on Latin. These are more updated and all that good stuff but now they are scattered all over my house and I can never find the right one by the bedside. Each one separately covers each of the 5 Latin Dances.
2. Technique of Latin American Dancing by Walter Laird is the other wonderful book with its supplement. I believe this is the official book of IDTA.