BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Wundt, Wilhelm Dating: 23.05.1871
BRIEF [O.A.] Haeckel, Agnes (geb. Huschke) Author: Haeckel, Agnes (geb. Huschke) Recipient: Haeckel, Ernst Dating: ??.??.1871
BRIEF [O.A.] Haeckel, Agnes (geb. Huschke) Author: Haeckel, Agnes (geb. Huschke) Recipient: Haeckel, Ernst Dating: 18.03.1871
BRIEF [O.A.] Haeckel, Agnes (geb. Huschke) Author: Haeckel, Agnes (geb. Huschke) Recipient: Haeckel, Ernst Dating: 25.03.1871