BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Michels, Victor Karl Theodor Dating: 24.06.1916
ABSCHRIFT Paulssen, Arnold Author: Paulssen, Arnold Recipient: Haeckel, Ernst Corporation: Kultusministerium des Freistaates Sachsen Weimar Eisenach Dating: 11.07.1919
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Carl & Charlotte [Eltern] Dating: 17.08.1859
POSTKARTE Wereschtschagin, Wassili Author: Wereschtschagin, Wassili Recipient: Haeckel, Ernst Dating: 27.03.1901
BRIEF [O.A.] Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 28.07.1881