BRIEF [O.A.] Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Dating: 19.06.1902
BRIEF [O.A.] Harperath, Ludw... Author: Harperath, Ludw... Recipient: Haeckel, Ernst Corporation: Universidad de Cordoba Dating: 20.12.1903