Dobro 1930s to present Founded 1929 by John Dopyera, Los Angeles. Now owned by Gibson.

http://www.provide.net/~cfh/dobro.html

http://www.resoguit.com/

http://en.wikipedia.org/wiki/Dobro

1974 Dobro Catalog http://www.resoguit.com/catalog.html

Dobro also made guitars under the following brand names:
Norwood Chimes, Broman, Angelus, Montgomery Ward, and Penetro. After World War II – Hound Dog, DB Original, and Replica 66. [Source:  The Hawaiian Steel Guitar and Its Great Hawaiian Musicians By Lorene Ruymar ]

Dobro reference books

Dobro Guitars – A Pictorial History

Forum

http://steelguitarforum.com

Image 1981 Dobro serial number eBay: