A Passion for Tango
This book really helps you understand what it is about tango that makes it so appealing to dancers and so addictive. Not only does David Turner tell you about the history of it but also the background of logic that allows you to understand why certain movements work. He has lots of great exercises for improving connection between partners and helpful tips about ochos, giros, ganchos etc.
This book is quite different from so many other books about tango. It's the perfect companion book for anyone who wants to follow up a class. You can dip into it as you want, but because of the light and amusing way it is writen, you might want to read it all the way through. David writes, not from the perspective of a teacher, although he is one, but from the viewpoint of a learner so, every now and then, you get a sort of "Aaaah!" moment when something you felt yourself comes up.