BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 30.05.1917
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 05.06.1917
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 17.06.1917
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 04.03.1917
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 24.04.1917