BRIEF OHNE UMSCHLAG Bender, Hedwig Author: Bender, Hedwig Recipient: Haeckel, Ernst Dating: 01.01.1898
BRIEF OHNE UMSCHLAG Bender, Hedwig Author: Bender, Hedwig Recipient: Haeckel, Ernst Dating: 30.04.1898
BRIEF OHNE UMSCHLAG Antipa, Grigore Author: Antipa, Grigore Recipient: Haeckel, Ernst Corporation: Muzeul de Istorie Naturala Dating: 14.01.1898