BRIEF [O.A.] Ernst [Prinz von Sachsen-Altenburg] Author: Ernst [Prinz von Sachsen-Altenburg] Recipient: Haeckel, Ernst Dating: 15.05.1905
BRIEF [O.A.] Ernst [Prinz von Sachsen-Altenburg] Author: Ernst [Prinz von Sachsen-Altenburg] Recipient: Haeckel, Ernst Dating: 14.12.1907
BRIEF [O.A.] Baffi, Freia Gisela Author: Baffi, Freia Gisela Recipient: Haeckel, Ernst Dating: 16.02.1914
BRIEF [O.A.] Vosberg Author: Vosberg Recipient: Haeckel, Ernst Corporation: Der Magistrat der Residenzstadt Postdam Dating: 29.01.1919
BRIEF [O.A.] Vosberg Author: Vosberg Recipient: Haeckel, Ernst Corporation: Der Oberbürgermeister Dating: 11.01.1919
BRIEF [O.A.] Schlicht, von [?] Author: Schlicht, von [?] Recipient: Haeckel, Ernst Dating: 14.07.1876
