BRIEF OHNE UMSCHLAG Fischer, Gustav Author: Fischer, Gustav Recipient: Haeckel, Ernst Dating: 25.11.1883
BRIEF [O.A.] Gerhardt, Dietrich Author: Gerhardt, Dietrich Recipient: Haeckel, Ernst Dating: 01.08.1883
BRIEF OHNE UMSCHLAG Göldi, Emil August Author: Göldi, Emil August Recipient: Haeckel, Ernst Dating: 28.04.1883
BRIEF [O.A.] Göldi, Emil August Author: Göldi, Emil August Recipient: Haeckel, Ernst Dating: 27.05.1883