BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 20.02.1913
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 03.03.1913
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 08.05.1913
BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 19.06.1913
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 18.10.1913
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Bölsche, Wilhelm Dating: 06.12.1913