POSTKARTE Weißenborn, Wilhelm Author: Weißenborn, Wilhelm Recipient: Haeckel, Ernst Dating: 08.04.1892
BRIEF [O.A.] Dreyer, Friedrich Author: Dreyer, Friedrich Recipient: Haeckel, Ernst Dating: 10.12.1884
BRIEF [O.A.] Eisenhardt, Friedr... Author: Eisenhardt, Friedr... Recipient: Haeckel, Ernst Dating: 10.03.1917
BRIEF OHNE UMSCHLAG Zimmermann, Otto Author: Zimmermann, Otto Recipient: Haeckel, Ernst Dating: 08.10.1875
BRIEF OHNE UMSCHLAG Zimmermann, Otto Author: Zimmermann, Otto Recipient: Haeckel, Ernst Dating: 12.10.1877
BRIEF OHNE UMSCHLAG Zimmermann, Otto Author: Zimmermann, Otto Recipient: Haeckel, Ernst Dating: 10.12.1880
BRIEF OHNE UMSCHLAG Zimmermann, Otto Author: Zimmermann, Otto Recipient: Haeckel, Ernst Dating: 27.07.1882
TODESANZEIGE Zimmermann, Auguste Author: Zimmermann, Auguste Recipient: Haeckel, Ernst Dating: 03.03.1884
BRIEF OHNE UMSCHLAG Zimmermann, Otto Author: Zimmermann, Otto Recipient: Haeckel, Ernst Dating: 10.10.1881