BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 24.12.1904
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 1904.12.?? [?]
BRIEF [O.A.] Georgii, Eberhard Author: Georgii, Eberhard Recipient: Haeckel, Ernst Dating: 15.02.1904