BRIEF [O.A.] Chapman, Henry C... Author: Chapman, Henry C... Recipient: Haeckel, Ernst Dating: 23.10.1872
BRIEF OHNE UMSCHLAG Costenoble, Hermann Author: Costenoble, Hermann Recipient: Haeckel, Ernst Corporation: Verlags-Buchhandlung Dating: 06.07.1872
BRIEF [O.A.] Bucchich, Gregorio Author: Bucchich, Gregorio Recipient: Haeckel, Ernst Dating: 09.08.1872
BRIEF [O.A.] Finsch, Otto Author: Finsch, Otto Recipient: Haeckel, Ernst Corporation: Verein für die Deutsche Nordpolarfahrt Dating: 05.03.1872