POSTKARTE Breitenbach, Wilhelm Author: Breitenbach, Wilhelm Recipient: Haeckel, Ernst Dating: 15.10.1896
POSTKARTE Reinicke, Emanuel Author: Reinicke, Emanuel Recipient: Haeckel, Ernst Corporation: Wilhelm Engelmann Verlagsbuchhandlung Dating: 29.09.1896
POSTKARTE Preyer, William Thierry Author: Preyer, William Thierry Recipient: Haeckel, Ernst Dating: 01.01.1896