'A Short Illustrated History of the Harrington and Richardson Arms Company (1871-1960)" by Joseph T. Vorsek is a good general history of the company and most of their products. It is available from www.cornellpublications.com
I also have found the H & R section of "Bluebook of Gun Values", 34th Edition, by S.P. Fjestasd to be most informative concerning the various handgun models H & R produced. No pictures but great word descriptions.