BRIEF [O.A.] Drewenthal, Wilhelm Author: Drewenthal, Wilhelm Recipient: Haeckel, Ernst Dating: 16.09.1884
BRIEF [O.A.] Schneider, G... H... Author: Schneider, G... H... Recipient: Haeckel, Ernst Dating: 20.03.1884
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 07.06.1884
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 08.10.1884
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 24.01.1884