PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 03.12.1909
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 30.12.1909
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Meyer, Frau von Arndt Meyer Dating: 28.02.1909
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Barbosa, Saturnigo Dating: 09.11.1909