This item has the words: "BILLET DE CORRESPONDENCE" printed upon it. This is probably a note to a publisher regarding an original composition of either Clara or Robert Schumann's. It refers to a correction that should be made to the Titelblatt or front page.
Schumann, Clara, 1819-1896. "Correspondence card by Clara Schumann." http://hdl.handle.net/1911/13031.
Schumann, Clara, 1819-1896--Correspondence
Digital version published by Brown Fine Arts Library, Fondren Library, Rice University