Here are some distinctive styles of “POST CARD”. Otherwise, try my Publishers’ Initials Logos and Series page.
Carlo Bassani

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
Langsdorf

Lichtenstern & Hariri

Modiano

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

Societa Editrice

Trenkler

Valentine & Sons

Wyndham & Company

Lawrence of Dublin used the same design albeit sometimes in green.