BRIEF OHNE UMSCHLAG Giltsch, Adolf Author: Giltsch, Adolf Recipient: Haeckel, Ernst Dating: 19.12.1903
BRIEF [O.A.] Ziegler, Heinrich Ernst Author: Ziegler, Heinrich Ernst Recipient: Haeckel, Ernst Dating: 25.11.1903
BRIEF [O.A.] Ziegler, Heinrich Ernst Author: Ziegler, Heinrich Ernst Recipient: Haeckel, Ernst Dating: 10.12.1903
BRIEF [O.A.] Eggeling, Heinrich von Author: Eggeling, Heinrich von Recipient: Haeckel, Ernst Dating: 31.12.1903