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 [O.A.] Griessmann, Bruno Author: Griessmann, Bruno Recipient: Haeckel, Ernst Dating: 19.08.1907
BRIEF [O.A.] Grimme, Emil A... Author: Grimme, Emil A... Recipient: Haeckel, Ernst Dating: 11.03.1915
BRIEF [O.A.] Eber, Almi Author: Eber, Almi Recipient: Haeckel, Ernst Corporation: Verein Merkur Dating: 05.06.1883