BRIEF OHNE UMSCHLAG Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Julius Dating: 20.02.1903
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Julius Dating: 30.04.1919
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Julius Dating: 17.07.1919
