BRIEF [O.A.] Miklucho-Maclay, Nikolaj N... Author: Miklucho-Maclay, Nikolaj N... Recipient: Haeckel, Ernst Dating: 27.06.1869
BRIEF [O.A.] Weschniakoff, Theodor Author: Weschniakoff, Theodor Recipient: Haeckel, Ernst Dating: 28.01.1869