BRIEF [O.A.] Martens, Eduard von Author: Martens, Eduard von Recipient: Haeckel, Ernst Dating: 20.05.1865
BRIEF [O.A.] Martens, Eduard von Author: Martens, Eduard von Recipient: Haeckel, Ernst Dating: 22.07.1865
BRIEF [O.A.] Martens, Eduard von Author: Martens, Eduard von Recipient: Haeckel, Ernst Dating: 28.11.1865