POSTKARTE Erdmann, Gustav Adolf Author: Erdmann, Gustav Adolf Recipient: Haeckel, Ernst Dating: 30.10.1895
BRIEF [O.A.] Döderlein, Ludwig Author: Döderlein, Ludwig Recipient: Haeckel, Ernst Dating: 04.10.1895
BRIEF OHNE UMSCHLAG Carneri, Bartholomäus von Author: Carneri, Bartholomäus von Recipient: Haeckel, Ernst Dating: 18.11.1895
BRIEF OHNE UMSCHLAG Carneri, Bartholomäus von Author: Carneri, Bartholomäus von Recipient: Haeckel, Ernst Dating: 22.12.1895
BRIEF [O.A.] Frankfurter, Otto Author: Frankfurter, Otto Recipient: Haeckel, Ernst Dating: 21.01.1895