BRIEF [O.A.] Behm, Hans Wolfgang Author: Behm, Hans Wolfgang Recipient: Haeckel, Ernst Dating: 15.07.1910
BRIEF [O.A.] Behm, Hans Wolfgang Author: Behm, Hans Wolfgang Recipient: Haeckel, Ernst Dating: 28.11.1910
POSTKARTE Ziegelmüller, Franz Author: Ziegelmüller, Franz Recipient: Haeckel, Ernst Dating: 03.12.1910