BRIEF OHNE UMSCHLAG Gombart, Ludwig Lucas von Author: Gombart, Ludwig Lucas von Recipient: Haeckel, Ernst Dating: 26.08.1872
BRIEF [O.A.] Gerstel, Gustav Author: Gerstel, Gustav Recipient: Haeckel, Ernst Corporation: Hannoversche Presse Dating: 23.03.1872
BRIEF OHNE UMSCHLAG Weismann, August Author: Weismann, August Recipient: Haeckel, Ernst Dating: 11.01.1872