Hatashita and Kodokan Gear should have the books in stock. And if you're looking for a complete breakdown of a single move, get the books.
Yes the ones that I have read are worth it. They break down techniques from many different situations. I would suggest picking one book on a throw that you like and do often. You will see so many views that you never thought of. For the most part now I just look stuff up on youtube as it is free. I have always picked mine up from Hatashita at tournaments in Ontario.
