BRIEF [O.A.] Diesterweg, Eleonore Author: Diesterweg, Eleonore Recipient: Haeckel, Ernst Dating: 17.12.1899
BRIEF [O.A.] Diesterweg, Eleonore Author: Diesterweg, Eleonore Recipient: Haeckel, Ernst Dating: 19.12.1899
POSTKARTE Erdmann, Gustav Adolf Author: Erdmann, Gustav Adolf Recipient: Haeckel, Ernst Dating: 08.10.1899
BRIEF [O.A.] Dieckmann, Gertha Author: Dieckmann, Gertha Recipient: Haeckel, Ernst Dating: 08.12.1899
