BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Reimer, Georg Dating: 18.04.1876
BRIEF [O.A.] Sloman, Robert Miles jr. Author: Sloman, Robert Miles jr. Recipient: Haeckel, Ernst Dating: 27.02.1902
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich von Dating: 05.01.1907
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich von Dating: 05.01.1907
ANSICHTSKARTE Kölliker, Albert von Author: Kölliker, Albert von Recipient: Haeckel, Ernst Dating: ??.??.1896