BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 16.08.1891
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 13.11.1891
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 31.12.1891