Frank de Haas' Single Shot Rifles and Actions, Mister Single Shot's Gunsmithing Idea Book and Bolt Action Rifles, Townsend Whelen's Mister Rifleman, James Grant's single shot series, Ned Roberts' & Ken Waters' breechloading single shot book, Michael Petrov's Custom Gunmakers of the 20th Century and Steve Hughes' Custom Rifles in Black and White. That's enough for a good start on both the aesthetics and the mechanics. Ned Roberts' earlier work on caplock target rifles was also a big influence for me. There are 40-50 more really top-drawer books but these are some of the ones I consider to be seminal.
My inclusion of Michael's and Steve's relatively recent works is not mere lip service to colleagues but rather is based upon my sincere opinion of the contents and their value to both existing and future enthusiasts. I only wish that these books contained more photos & descriptions of the frequently unique & fascinating details of the rifles' styling and mechanics, things like closeup shots of the Barney Worthen 1903 bolt lock or the Shelhamer grip strap for instance. This last comment is meant strictly as constructive criticism, my admiration for these books and their authors is tremendous and I await their next works eagerly.
Regards, Joe