One of the best books I've found is "The Samurai Sword" by John M. Yumoto.
The publisher is Charles E. Turtle Company, Inc. The ISBN # is
0-8048-0509-1. The book is a good start for learning the history, and
identification of Japanese swords. While not the last word in
identification, it is one of the more readily available works on the
market.
Enjoy,
Tim Harrod
Steel Dragon Armory