BRIEF OHNE UMSCHLAG Sarasin, Fritz Author: Sarasin, Fritz Recipient: Haeckel, Ernst Dating: 14.09.1908
BRIEF OHNE UMSCHLAG Sokolowsky, Alexander Author: Sokolowsky, Alexander Recipient: Haeckel, Ernst Dating: 13.07.1908
BRIEF OHNE UMSCHLAG Gruyter, Walter de Author: Gruyter, Walter de Recipient: Haeckel, Ernst Dating: 19.07.1908
BRIEF OHNE UMSCHLAG Keller, Conrad Author: Keller, Conrad Recipient: Haeckel, Ernst Dating: 19.07.1908