BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Ehlers, Ernst Dating: 28.12.1872
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Norman, Alfred Merle Dating: 1872:??.?? [oder später]
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Virchow, Rudolf Dating: 11.10.1872
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Reimer, Ernst Dating: 20.02.1872
