Four books: i) U.S. Military Knives Bayonets & Machetes. Book III by M.H. Cole, ii) Commando Dagger. The Complete Illustrated History pf the Fairbairn-Sykes Fighting Knife by L. Thompson, iii) Fighting Knives. An Illustrated Guide to Fighting Knives and Military Survival Weapons of the World by F.J. Stephens, Daggers & Fighting Knives of the Western World by H.L. Peterson.