BRIEF OHNE UMSCHLAG Bergmann, Anton Author: Bergmann, Anton Recipient: Haeckel, Ernst Dating: 15.02.1909
BRIEF OHNE UMSCHLAG Bergmann, Anton Author: Bergmann, Anton Recipient: Haeckel, Ernst Dating: 21.06.1911
BRIEF OHNE UMSCHLAG Bergmann, Anton Author: Bergmann, Anton Recipient: Haeckel, Ernst Dating: 15.02.1914