BRIEF [O.A.] Hatschek, Berthold Author: Hatschek, Berthold Recipient: Haeckel, Ernst Dating: 28.11.1910
BRIEF [O.A.] Graedener, Hermann Author: Graedener, Hermann Recipient: Haeckel, Ernst Dating: 06.08.1910
BRIEF [O.A.] Topali, P... Sp... Author: Topali, P... Sp... Recipient: Haeckel, Ernst Dating: 17.10.1910
BRIEF [O.A.] Schimmelmann, Frh. Hugo von Author: Schimmelmann, Frh. Hugo von Recipient: Haeckel, Ernst Dating: 24.11.1910
BRIEF [O.A.] Schimmelmann, Frh. Hugo von Author: Schimmelmann, Frh. Hugo von Recipient: Haeckel, Ernst Dating: 29.12.1910