George Gruhn has been dealing in vintage guitars before they were considered vintage guitars.  This book is a culmination of his years of work as a guitar dealer.  He has been on the front lines of this business buying and selling all types of stringed instruments. He has been located in Nashville for many years and has been researching and keeping detailed records about guitars.  This book is as close as you can get to “Law” when you need to know about vintage guitars.  This book is a must for every guitar collector.  Check it out here, available at amazon.  Gruhn’s Guide to Vintage Guitars : An Identification Guide for American Fretted Instruments (2nd Ed)