BRIEF [O.A.] Engelhardt, Ewald Author: Engelhardt, Ewald Recipient: Haeckel, Ernst Dating: ??.11.1909
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.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 09.03.1905
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 05.05.1905
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 30.12.1905
BRIEF [O.A.] Engelsmann, Elisabeth Author: Engelsmann, Elisabeth Recipient: Haeckel, Ernst Dating: 1906.??.?? [?]