POSTKARTE Bölsche, Wilhelm; Bölsche, Johanna Author: Bölsche, Wilhelm; Bölsche, Johanna Recipient: Haeckel, Ernst Dating: 11.12.1900
POSTKARTE Waldeyer-Hartz, Wilhelm von Author: Waldeyer-Hartz, Wilhelm von Recipient: Haeckel, Ernst Dating: 28.04.1900