BRIEF [O.A.] Heim, Freiherr von Author: Heim, Freiherr von Recipient: Haeckel, Ernst Dating: 06.12.1899
BRIEF [O.A.] Heim, Freiherr von Author: Heim, Freiherr von Recipient: Haeckel, Ernst Dating: 05.06.1904
BRIEF [O.A.] Heim, Freiherr von Author: Heim, Freiherr von Recipient: Haeckel, Ernst Dating: 05.03.1899