BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rodenberg, Julius Dating: 15.02.1901
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Schultze, Leo Dating: 22.02.1901
BRIEF [O.A.] Gessner, J... F... L... Author: Gessner, J... F... L... Recipient: Haeckel, Ernst Dating: 15.05.1902
BRIEF [O.A.] Anton, Günther Kurt Author: Anton, Günther Kurt Recipient: Haeckel, Ernst Dating: 03.01.1901
ANSICHTSKARTE Basso, Fritzi von Author: Basso, Fritzi von Recipient: Haeckel, Ernst Dating: 07.03.1912
BRIEF [O.A.] Sluiter, C... Ph... Author: Sluiter, C... Ph... Recipient: Haeckel, Ernst Dating: 10.04.1882