BRIEF [O.A.] Renault, Hyacinthe Author: Renault, Hyacinthe Recipient: Haeckel, Ernst Dating: 14.12.1903
BRIEF [O.A.] Sethe-Seyberth, Luise Author: Sethe-Seyberth, Luise Recipient: Haeckel, Ernst Dating: 25.05.1903