BRIEF [O.A.] Martens, Eduard von Author: Martens, Eduard von Recipient: Haeckel, Ernst Dating: 30.12.1869
BRIEF [O.A.] Charisius, A. Author: Charisius, A. Recipient: Haeckel, Ernst Corporation: Lüderitz'sche Verlagsbuchhandlung Dating: 14.01.1869