BILDPOSTKARTE Kraigher-Porges, Josepha Author: Kraigher-Porges, Josepha Recipient: Haeckel, Ernst Dating: 31.03.1902
BILDPOSTKARTE Sarasin, Paul; Sarasin, Fritz Author: Sarasin, Paul; Sarasin, Fritz Recipient: Haeckel, Ernst Dating: 12.06.1910
BILDPOSTKARTE Becker, Franz Johann Jakob Emil Author: Becker, Franz Johann Jakob Emil Recipient: Haeckel, Ernst Dating: 20.08.1917