There are literally hundreds of books on knives and knife fighting. The following list are the books I have read and enjoyed.

The Ultimate Guide to Knife Combat by Black Belt Mag
The Complete Knife Throwing Guide by Gil Hibben
Book of Knives by Hank Reinhardt
Secrets of the karambit by David Seiwert
Knife Fighting by Tim Delavier
Blade Master by John Sanchez
Put Em down, Take em out by Don Pentecost
The complete book of knife fighting by William Cassidy
Knife Fighting, Knife Throwing by Michael Echanis
Military Knife Fighting by Robert K. Spear
Balisong Knife Fighting by Sid Campbell
Contemporary Knife Targeting by Grosz & Janich
Knife Fighting A Practical Course by Michael Janich
The Knife Fighting Method of Cold Steel
Knife Fighting by Sammy Franco
Master Of The Blade: Secrets Of The Deadly Art Of Knife Fighting
by Richard Ryan