BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Meyer, Hans Corporation: Universität Jena Dating: 06.05.1909
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Verworn, Josephine Dating: 28.02.1909
BRIEF [O.A.] Verworn, Max Author: Verworn, Max Recipient: Uslar-Gleichen, Bernhard von Dating: 12.01.1909
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Uslar-Gleichen, Luise von Dating: 28.02.1909
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Marx, Ernst Dating: 1909.??.?? [nach 20.03.1909]