From the Rubin Archives: From Bob Wills to Ray Benson, A History of Western Swing Music, Vol. 1, by Tom Dunbar
Tom Dunbar knew what he was talking about.
Beyond this self published book, check out his collected oral histories at Baylor University.
I bought this very informative thin tome from him at a book signing event at Antone's Records shortly after moving to Austin TX in 1988.