BRIEF [O.A.] Dahrenstaedt, Helene Author: Dahrenstaedt, Helene Recipient: Haeckel, Ernst Dating: 21.07.1904
BRIEF [O.A.] Dahrenstaedt, Helene Author: Dahrenstaedt, Helene Recipient: Haeckel, Ernst Dating: 22.10.1904
ANSICHTSKARTE Meyer, Hans et. al. Author: Meyer, Hans et. al. Recipient: Haeckel, Ernst Dating: 31.01.1904