BRIEF OHNE UMSCHLAG Kalisky, Friederike Author: Kalisky, Friederike Recipient: Haeckel, Ernst Dating: 15.02.1852
BRIEF OHNE UMSCHLAG Kalisky, Friederike, geb. Thomann Author: Kalisky, Friederike, geb. Thomann Recipient: Haeckel, Ernst Dating: 03.10.1848
POSTKARTE Bölsche, Wilhelm; Bölsche, Johanna Author: Bölsche, Wilhelm; Bölsche, Johanna Recipient: Haeckel, Ernst Dating: 15.09.1911
POSTKARTE Baehn-Naumann, Lisbeth Author: Baehn-Naumann, Lisbeth Recipient: Haeckel, Ernst Dating: 11.08.1919