BRIEF [O.A.] Zschacke, Fritz-Hermann Author: Zschacke, Fritz-Hermann Recipient: Haeckel, Ernst Dating: 12.12.1918
POSTKARTE Zschacke, Fritz-Hermann Author: Zschacke, Fritz-Hermann Recipient: Haeckel, Ernst Dating: 30.07.1915
BRIEF [O.A.] Zschacke, Fritz-Hermann Author: Zschacke, Fritz-Hermann Recipient: Haeckel, Ernst Dating: 08.08.1915
BRIEF [O.A.] Zschacke, Fritz-Hermann Author: Zschacke, Fritz-Hermann Recipient: Haeckel, Ernst Dating: 14.02.1916
BRIEF [O.A.] Zschacke, Fritz-Hermann Author: Zschacke, Fritz-Hermann Recipient: Haeckel, Ernst Dating: 13.02.1917