I have Levine's 5th edition as well as sargents 6th edition. Both are great references. Levine's guide is more pattern oriented and Sargent's seems more brand specific. In my opinion all of the guides have their strengths & weakness. I also picked up "The Standard Knife Collectors Guide", which has some great info as well as photos of your big knife makers as well as several others like IXL , Buck Creek , Winchester , etc. These are the 3 I own and use regularly. If I had to give up all but one I would probably keep Levine's.