BRIEF [O.A.] Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Dating: 20.12.1901
BRIEF OHNE UMSCHLAG Korab', Valdemar C. de Author: Korab', Valdemar C. de Recipient: Haeckel, Ernst Corporation: Instituto Moderno Dating: 19.05.1901
BRIEF [O.A.] Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Corporation: Instituto Moderno Dating: 26.09.1900
BRIEF OHNE UMSCHLAG Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Corporation: Instituto Moderno Dating: 14.06.1900