Ed--
Welcome to the forum. The STANDARD CATALOG OF S&W by Krause publications is probably the best single reference book on S&Ws. The first ed came out in the 1990s and there have been two more since. I don't know if Krause has plans for a 4th, but S&W has introduced several new models since the 3rd ed.
If you have a serious interest in older S&Ws, the first major book on S&W, by McHenry & Roper, has a lot of company history as well as gun info. The book by Robert Neal & Roy Jinks covering S&Ws made from the 1850s to 1945 is excellent. Roy Jinks wrote his own history of S&W ca 1977 (Beinfield Publishing, iirc) that has been reprinted over 15 times. John Henwood of Pacifica CA wrote & published AMERICA'S RIGHT ARM (a history of the M&P) ca 2003 in a limited edition of 500 softcover copies, which has a lot of info on the postwar versions of the K-frame.
Fyi, the official serial number of any S&W revolver is the number stamped on the bottom of the butt. Prior to 1957 when model numbers began appearing on the revolvers, the serial number also appeared on the rear face of the cylinder and the bottom of the barrel just forward of the frame. All those numbers should match on an "original" piece. The last three digits of the s/n were written or stamped on the inside of one of the wood stocks till about that time also.
The number on the yoke (the swing-out part that holds the cylinder) should match the number on the yoke cut in the frame on an original piece. Those are internal numbers used by the factory to keep major parts together during assembly, and that same number should be stamped on the inside of the sideplate if the gun is entirely original.
Some (military and possibly police) service guns will be found with sideplates replaced, and occasionally guns will be found with cylinders (and even barrels) taken from other guns. (See the thread asking for identification of a gun began by "Robin38" currently on this same page.)
I hope the above may be helpful to you.
