I was very lucky to have a member here give me all of his knife books, and they are quite informative. My favorite is the book about knives of Finland. I have picked up a few Knives Annuals here and there, edited by Ken Warner I believe. I found one used at the library for about a quarter, and picked up a couple at a local knife shop for free, he couldn't give them away. I've seen others for sale, one notably at a local PA gun store for about 20 bucks! One of our members here wrote a price guide on Case knives, and I got that at a store sale, for dirt cheap, they were going out of business, chain called Borders. A book called The Knife in Homespun America was recommended to me by Dan Schectman, he told me about it at Scott Gossmans Gosstoberfest or at the Chesapeake Knife Show, can't remember which. It is out of print, but I bought mine from an online muzzleloading dealer. I just ordered an old book called Firearms Traps and Tools of the Mountain Man, from Barnes and Noble. Lots of different blades covered, or so the advertisement read. Magazines like Backwoodsman and Knife World usually have some good articles on traditional blades, but Backwoodsman isn't always as accurate as Knifeworld. I bought a Remington Knives price guide at a small hole in the wall show for a couple dollars last year, great art and a long list of patterns used. A wealth of information. The recent Great Eastern book was pretty good. I bought an older Marbles knife book last year too.
One thing that I've noticed, in my frequent hauntings of large used book stores, is that knife books are few and far between. I've been hoping that a dog eared copy of Levines 4th Edition would fall off the shelf, and hopefully not land on my head, but I'd take it, for a great price, and I'd walk out with the famous go to learning tool for all of us knife nuts. Not yet, but I've gotten some great deals on knife books. I've been meaning to go through my books and give some away on here. They are a great reference. Sleep apnea mixed with insomnia is not a pretty picture, but I've spent some late nights and early mornings looking over these old books.
I could buy another GEC for that. 
