BILDPOSTKARTE Kükenthal, Willy Georg [et al.] Author: Kükenthal, Willy Georg [et al.] Recipient: Haeckel, Ernst Dating: 08.08.1901
BILDPOSTKARTE Ziegler, Heinrich Ernst Author: Ziegler, Heinrich Ernst Recipient: Haeckel, Ernst Dating: 13.08.1901
BILDPOSTKARTE Lindeman, Ferdinand P. Author: Lindeman, Ferdinand P. Recipient: Haeckel, Ernst Dating: 21.07.1901
BILDPOSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 22.12.1901