BRIEF [O.A.] Byron, Julian M... Author: Byron, Julian M... Recipient: Haeckel, Ernst Dating: 07.06.1906
BRIEF [O.A.] Cortines, Luis M... Author: Cortines, Luis M... Recipient: Haeckel, Ernst Dating: 05.11.1906
BRIEF [O.A.] Balestra, Juan; Soto, José C. Author: Balestra, Juan; Soto, José C. Recipient: Haeckel, Ernst Corporation: Comité Nacional del Libre Pensamiento Dating: 15.06.1906