BRIEF [O.A.] Fischer, F... L... Author: Fischer, F... L... Recipient: Haeckel, Ernst Dating: 16.02.1914
BRIEF [O.A.] Knoblauch, Carl Author: Knoblauch, Carl Recipient: Haeckel, Ernst Corporation: F. A. Christoph Dating: 22.10.1877
BRIEF [O.A.] Knoblauch, Carl Author: Knoblauch, Carl Recipient: Haeckel, Ernst Corporation: F. A. Christoph Dating: 21.04.1876
BRIEF [O.A.] Knoblauch, Carl Author: Knoblauch, Carl Recipient: Haeckel, Ernst Corporation: F. A. Christoph Dating: 26.04.1876