BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 11.02.1911
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 15.02.1911
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 22.03.1911
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 21.05.1911
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 09.06.1911
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 04.09.1911
BRIEF [O.A.] Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: ??.12.1911