I probably have 20 knifemaking books,a dozen videos,and 10 or so metallurgical and reference books.I still take a look at any book I run across that I don't have.Almost every teacher has some value to impart.Ed Fowler's books are also of use,and they make a good read.
Jim Hrisoulas produces the most extensive book(s) I have encountered.They are worth every penny of the cost.When I want to check on a steel or technique,I pick his book up.It sits at the side of my easy chair,where I do most of my planning and sketching.
Funny that other makers have trouble hanging on to Dave Boyes book.I have never lost track of a knife book on loan except that one.I have given several copies away to makers who have lost theirs.
SA