BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 16.02.????
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 24.04.1905
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 16.01.1906
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 1906.??.?? [?]
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 24.12.1911