POSTKARTE Bölsche, Wilhelm; Bölsche, Johanna Author: Bölsche, Wilhelm; Bölsche, Johanna Recipient: Haeckel, Ernst Dating: 09.08.1916
POSTKARTE Bölsche, Wilhelm; Bölsche, Karl Author: Bölsche, Wilhelm; Bölsche, Karl Recipient: Haeckel, Ernst Dating: 10.08.1916
BRIEF OHNE UMSCHLAG Bothe, Margarete Author: Bothe, Margarete Recipient: Haeckel, Ernst Dating: 20.08.1916