I've made some friction folders and penny knives and just finished a spring back that I copied from Smith's 1816 Key. I was going to use the same catalog for another folder- spring back- but then thought maybe I ought to check out some other knives. I could buy a lot of books, etc. and look at the photos but I was wondering if anyone knows of any on-line sources that might have detailed photos of well-proven, documented original spring back, folding knives. Thanks for any help or suggestions.