Charles W. Clawson's "Collector's Guide to Colt .45 Service pistols Models of 1911 and 1911A1 (third edition), "Colt . 45 Government Models (Commercial Series): 1912 Through 1970" (third edition), and "Colt .45 Service Pistols Models of 1911 and 1911A1: Complete Military History Development and Production 1900 Through 1945" (1991).

The three books are excellent.