PORTRÄTPOSTKARTE Friederici, Erna Author: Friederici, Erna Recipient: Haeckel, Ernst Dating: 24.12.1908
PORTRÄTPOSTKARTE Meyer, Lotte Author: Meyer, Lotte Recipient: Haeckel, Ernst Dating: 1914.??.?? [ca.]
PORTRÄTPOSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 24.12.1913
PORTRÄTPOSTKARTE Haeckel, Emma Author: Haeckel, Emma Recipient: Haeckel, Ernst & Agnes [Eltern] Dating: 21.04.1915
PORTRÄTPOSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 11.03.1910