BRIEFABSCHRIFT Haeckel, Ernst Author: Haeckel, Ernst Recipient: Eggeling, Heinrich von Dating: 07.07.1888
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Dodel-Port, Arnold Dating: 03.01.1888
BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hesse-Wartegg, E. von Dating: 25.01.1888
