Very nice article on the Model 3 in the May - June 23 issue of Military Antique Collector Magazine by Tim Prince. If you are not a subscriber I am sure back issues will be available.
I believe Roy Double's private monograph of about 50+ yrs ago was the earliest detailed publication on the American models, however you can't beat Charlie Pate's book " Smith & Wesson American Model " for all you ever need to know about them. Ed