Theo Stroefer, Nürnberg (T.S.N.)

Theodor Stroefer is actually the subject of a Wikipedia article. This describes his activity as a publisher of illustrated books, which started well before the postcard era. It mentions his postcard activities as a “sideline”, but this was a big area of business activity when it first came on the scene. The TPA site (see refs) identifies printers used by the firm. The first example card was printed by Ackermann for example. Some cards name the firm on the address side, others just use initials and/or a logo.