Where to begin. Well I will throw out these one:

Best Judo By Inokuma, Isao and Sato, Noboyuki.

Judo Formal Techniques: A Complete Guide to Kodokan Randori No Kata By Draeger, & Don Otaki, Tadao

Kodokan Judo Throwing Techniques By Daigo, Toshiro

Well there are more but these ones are the first to pop into my head that are readily available.

Born for the Mat by Fukuda, Keiko is a good book on Ju no kata but is rather rare.(There is a newer re-issue of the book that is readily available but, it is said that is not as informative as the original.)