BRIEF [O.A.] Dybowski, Benedykt Author: Dybowski, Benedykt Recipient: Haeckel, Ernst Dating: 30.03.1902
BRIEF [O.A.] Dybowski, Benedykt Author: Dybowski, Benedykt Recipient: Haeckel, Ernst Dating: 17.04.1902
BRIEF OHNE UMSCHLAG Dybowski, Benedykt Author: Dybowski, Benedykt Recipient: Haeckel, Ernst Dating: 30.03.1902