There are several guides addressing watches, along the lines of "The Complete Price Guide to Watches" written by Tom Engle, which can make a decent place to start. It doesn't include vintage pocket watches exclusively, nonetheless it goes into a reasonable amount of detail concerning them. When seeking the correct data to use, don't just adhere to a single source. Gather info from different places and compare the details and trivia presented. You'll be surprised concerning how the info varies and matches, particularly on pricing and value.