BILDPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Heldburg, Helene von Dating: 02.04.1919
BILDPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 01.04.1919
BILDPOSTKARTE Haeckel, Emma Author: Haeckel, Emma Recipient: Haeckel, Ernst & Agnes [Eltern] Dating: 13.04.1919