BRIEF [O.A.] Eurinac, Adolf E... Author: Eurinac, Adolf E... Recipient: Haeckel, Ernst Dating: 18.09.1887
BRIEF [O.A.] Döderlein, Ludwig Author: Döderlein, Ludwig Recipient: Haeckel, Ernst Dating: 04.12.1887
BRIEF [O.A.] Cattaneo, Giacomo Author: Cattaneo, Giacomo Recipient: Haeckel, Ernst Dating: 22.12.1887
BRIEF [O.A.] Eimer, Theodor Author: Eimer, Theodor Recipient: Haeckel, Ernst Corporation: Direktion des zoologischen Instituts der Universität Tübingen Dating: 29.06.1887