BRIEF [O.A.] Hatschek, Berthold Author: Hatschek, Berthold Recipient: Haeckel, Ernst Dating: 28.11.1910
BRIEF [O.A.] Scherzer, Ritter Karl von Author: Scherzer, Ritter Karl von Recipient: Haeckel, Ernst Dating: 16.05.????
BRIEF [O.A.] Graedener, Hermann Author: Graedener, Hermann Recipient: Haeckel, Ernst Dating: 18.12.1912
BRIEF [O.A.] Graedener, Hermann Author: Graedener, Hermann Recipient: Haeckel, Ernst Dating: 16.02.1913
BRIEF [O.A.] Graedener, Hermann Author: Graedener, Hermann Recipient: Haeckel, Ernst Dating: 30.11.1914
BRIEF [O.A.] Graeser, Emma Author: Graeser, Emma Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Carl Graeser & Co. Dating: 22.06.1903
