BRIEFABSCHRIFT Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich von Dating: 03.11.1890
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich von Dating: 30.12.1890
BRIEFENTWURF Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich von Dating: 20.01.1890
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich von Dating: ??.03.1890