BRIEF [O.A.] Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Dating: 14.01.1904
BRIEF [O.A.] Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Dating: 05.02.1905
BRIEF [O.A.] Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Dating: 15.09.1905
BRIEF [O.A.] Korab', Valdemar C... de Author: Korab', Valdemar C... de Recipient: Haeckel, Ernst Dating: 21.01.1906