BRIEF OHNE UMSCHLAG Leporin, Valerie Author: Leporin, Valerie Recipient: Haeckel, Ernst Dating: 04.11.1913
BRIEF OHNE UMSCHLAG Wichmann, Carl Author: Wichmann, Carl Recipient: Haeckel, Ernst Dating: 30.12.1913
BRIEF OHNE UMSCHLAG Wichmann, Carl Author: Wichmann, Carl Recipient: Haeckel, Ernst Dating: 13.02.1913
BRIEF OHNE UMSCHLAG Wichmann, Carl Author: Wichmann, Carl Recipient: Schmidt, Heinrich Dating: 11.02.1913