So this is pretty cool. I got myself a copy of a 1925 Ray-O-Vac Radio Operating Manual and Broadcast Station Directory. The manual contains a number of battery advertisements, and describes the proper use and care of said radio.
There are not a lot of radio directories from this era. The renowned Barry Mishkind keeps a list here. But this Ray-O-Vac list appears to be unique. Interestingly lists it's own AM radio directory including the U.S., Canada and Mexico.The book adds up to 64 pages squeezed into a 21MB pdf. I have scanned it for your arcane reading pleasure.