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

1974 Dobro Catalog

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


Image 1981 Dobro serial number eBay: