BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Uslar-Gleichen, Bernhard von Dating: 19.02.1917
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Elisabeth Dating: 20.08.1917
BRIEF OHNE UMSCHLAG Grober, Julius Author: Grober, Julius Recipient: Haeckel, Ernst Dating: 10.07.1917
BILDPOSTKARTE Grimsehl, Carl; Grimsehl, M. Author: Grimsehl, Carl; Grimsehl, M. Recipient: Haeckel, Ernst Dating: 22.09.1917
BRIEF OHNE UMSCHLAG Grober, Julius Author: Grober, Julius Recipient: Haeckel, Ernst Dating: 30.04.1917