BILDPOSTKARTE Bos-Vernet, Clara Author: Bos-Vernet, Clara Recipient: Haeckel, Ernst Dating: 17.12.1905
BILDPOSTKARTE Bertheau, Georg; Bertheau, Amelie, geb. Kimich Author: Bertheau, Georg; Bertheau, Amelie, geb. Kimich Recipient: Haeckel, Ernst Dating: 01.01.1906
BILDPOSTKARTE Becker, Franz Johann Jakob Emil Author: Becker, Franz Johann Jakob Emil Recipient: Haeckel, Ernst Dating: ??.??.1913