BRIEF OHNE UMSCHLAG Ohe, Bour von der Author: Ohe, Bour von der Recipient: Haeckel, Ernst Dating: 06.06.1904
BRIEF OHNE UMSCHLAG Delprat, Theodore Author: Delprat, Theodore Recipient: Haeckel, Ernst Dating: 16.08.1904
BRIEF OHNE UMSCHLAG Delprat, Theodore Author: Delprat, Theodore Recipient: Haeckel, Ernst Dating: 30.06.1904
TELEGRAMM Versluys, Jan; Kampen, Pieter Nicolaas van [et al.] Author: Versluys, Jan; Kampen, Pieter Nicolaas van [et al.] Recipient: Haeckel, Ernst Dating: 17.02.1904