BRIEF [O.A.] Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 28.07.1881
BRIEF [O.A.] Sloman, Robert Miles jr. Author: Sloman, Robert Miles jr. Recipient: Haeckel, Ernst Dating: 27.02.1902
BRIEF [O.A.] Schild, Johann Author: Schild, Johann Recipient: Haeckel, Ernst Corporation: Deutsch-Australische-Dampfschiffs-Gesellschaft Dating: 13.03.1901