There are three versions of ABC - ordinary print, slightly decorative print and constrained into a vertical diamond shape. The printed A.B.C. occurs on early (undivided) German cards. The examples are French,
I don't know whether these are the same or different publishers.
Although card 2653 was written in 1942, it looks ten or so years older.
ABC is a common element in logos, there are several post-WW2 topo marques -
eg
"A.B.C. Photographie Industrielle, Marseille",
"Imprimerie ABC, 9 rue Blacas, Nice" and "ABC Verlag, Bern".
Achille Brioschi & C, Milan, the makers of Lysoform, also produced advertising postcards with an ABC logo but these are clearly identified by name on the card.
