History of advertising: No 160: The first radio commercials | Campaign US
Antique radio - Wikipedia
Buyers' Market for Vintage Radios, Phonographs, and Related Equipment | Maine Antique Digest
Radio Manufacturers of the 1920's, Vol. 1 - A-C Dayton to J. B. Ferguson, Inc. by Alan Douglas - Paperback - from Lloyd Zimmer, Books and Maps (SKU: 038837)
Radio Manufacturers of the 1920's Volume 1 hardback US pub valve tube Wireless | eBay
Radio Manufacturers of the 1920s, Vol. 1, A-C Dayton to J.B. Ferguson, Inc. 9781886606029 | eBay
Radio Manufacturers of the 1920's: Vol. 2: Alan Douglas: 9781886606005: Amazon.com: Books
Crosley Radio models - sources for the beginning 1921-1930 | Radiomuseum
File:Early 1920s radio and horn speaker.png - Wikimedia Commons