Here are some distinctive styles of “POST CARD”. Otherwise, try my Publishers’ Initials Logos and Series page.
Blum & Degen
Golike & Wilburg
Knackstedt & Näther
K&N produced cards for a number of Scandinavian publishers in a distinctive font and wording.
Source: Famgus Vykort
Lichtenstern & Hariri
The elaborate A in the first line of the address is perhaps more memorable than the postcard heading.
PB, Harlesden, London N.W.
Ritter & Kloeden
Rotary Photographic Company Ltd
The Rotograph Company, New York
Valentine & Sons
Wyndham & Company
Lawrence of Dublin used the same design albeit sometimes in green.