BRIEF [O.A.] Schlichting, Marie Author: Schlichting, Marie Recipient: Haeckel, Ernst Dating: 15.03.1910
BRIEF [O.A.] Schlichting, Marie Author: Schlichting, Marie Recipient: Haeckel, Ernst Dating: 19.02.1915
BRIEF [O.A.] Schlichting, Marie Author: Schlichting, Marie Recipient: Haeckel, Ernst Dating: 20.11.1918