BILDPOSTKARTE Haynes, Frank Jay; Haynes, Jack Author: Haynes, Frank Jay; Haynes, Jack Recipient: Haeckel, Ernst Dating: 17.08.1907
BILDPOSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 15.04.1899
BILDPOSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 03.05.1899