BILDPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Heldburg, Helene von Dating: 02.04.1919
BILDPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Heldburg, Helene von Dating: 31.12.1909
BILDPOSTKARTE Ludowici, Wilhelm Author: Ludowici, Wilhelm Recipient: Haeckel, Ernst Dating: 22.05.1916
BILDPOSTKARTE Klinghammer, Waldemar Author: Klinghammer, Waldemar Recipient: Haeckel, Ernst Dating: 31.12.1903
BILDPOSTKARTE Friedrich, Gustav Author: Friedrich, Gustav Recipient: Haeckel, Ernst Dating: 15.02.1914