BRIEF OHNE UMSCHLAG Hübner, Max; Hübner, Maria Author: Hübner, Max; Hübner, Maria Recipient: Haeckel, Ernst Dating: 14.02.1909
BRIEF OHNE UMSCHLAG Floerke, Wilhelm (Willy) Author: Floerke, Wilhelm (Willy) Recipient: Haeckel, Ernst Dating: 16.02.1909