POSTKARTE Amsberg, August von Author: Amsberg, August von Recipient: Haeckel, Ernst Dating: 16.05.1897
BRIEF [O.A.] Beisswanger, Konrad Author: Beisswanger, Konrad Recipient: Haeckel, Ernst Corporation: Konrad Beisswanger's Buchdruckerei und Verlag Dating: 19.03.1908
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Agnes Dating: 23.08.1868
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Carl Gottlob; Haeckel, Charlotte Dating: 23.08.1868
