BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Delle Grazie, Marie Eugenie Dating: 19.08.1910
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Heldburg, Helene von Dating: 30.05.1910
POSTKARTE Haeckel, Ernst Franz Max Author: Haeckel, Ernst Franz Max Recipient: Haeckel, Ernst Dating: 15.02.1910