BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich Dating: 12.12.1890
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich Dating: 20.01.1890
BRIEFABSCHRIFT Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich Dating: 12.01.1890