Hank has a very good handle on it!
One of my favorites is The 1990 Trails Among the Columbine. It has many maps, great color photographs and many photographs that don't seem to be in any other books.
The Marshall Pass by Borneman is also great. Good history information, and also again many photographs that I haven't seen in other books. It has many firsthand recollections from the folks that worked the line from the old Postmaster at the Marshall Pass station (Gus Latham) to Engineers (Frank Veo), Fireman, and brakemen/conductors (Ted Mcdowell). Heck there is even a lady that used to cook for crews that were laid over in Sargent but I can't recall her name at the moment. Great read, definitely.
The Gunnison book by Richard Dorman is also a good book. Many maps, information and photographs I haven't seen before.
Ross Miller