POSTKARTE Wereschtschagin, Wassili Author: Wereschtschagin, Wassili Recipient: Haeckel, Ernst Dating: 27.03.1901
POSTKARTE Grazie, Marie Eugenie delle Author: Grazie, Marie Eugenie delle Recipient: Haeckel, Ernst Dating: 22.08.1903
POSTKARTE Osborn, Henry Fairfield Author: Osborn, Henry Fairfield Recipient: Haeckel, Ernst Dating: ??.??.1906
