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
BRIEF [O.A.] Waldthausen, Julius Freiherr von Author: Waldthausen, Julius Freiherr von Recipient: Haeckel, Ernst Corporation: Deutsche Gesandtschaft Dating: 11.03.1907
BILDPOSTKARTE Schuster, Adolf Niklaus Author: Schuster, Adolf Niklaus Recipient: Haeckel, Ernst Dating: 16.05.1909
POSTKARTE Schuster, Adolf Niklaus Author: Schuster, Adolf Niklaus Recipient: Haeckel, Ernst Dating: 11.03.1910
BRIEF [O.A.] Schneiders, Carlos Author: Schneiders, Carlos Recipient: Haeckel, Ernst Dating: 15.04.1912
POSTKARTE Hopcevic, Spiridion jun. Author: Hopcevic, Spiridion jun. Recipient: Haeckel, Ernst Dating: 11.03.1907
BRIEF [O.A.] Sangmineti, Alfred Geróme Author: Sangmineti, Alfred Geróme Recipient: Haeckel, Ernst Dating: 21.12.1904