Having grown up totally torn between the writings of the two Idaho scribes -- Jack O'Connor and Elmer Keith, I'm now a big fan of the writings of Askins Sr. Don't much care for Jr. The American Shotgun is the first of his books I got. I now also have Modern Shotguns and Loads, Game Bird Shooting, Shotgun-ology, and a slew of Western Cartridge Co. pamphlets on their Super-X shotgun shells that he wrote. The Captains tie in with the development of the Super-Fox I've had since I was 17, doesn't hurt either.
You might find this lengthy thread from Shotgun World on Capt Askins Superposed interesting --
http://www.shotgunworld.com/bbs/viewtopic.php?t=124719
