POSTKARTE Fischer, S... Author: Fischer, S... Recipient: Haeckel, Ernst Corporation: S. Fischer, Prot. Wechselstube Dating: 19.04.1905
BRIEF OHNE UMSCHLAG Kirsch, Arnold Author: Kirsch, Arnold Recipient: Haeckel, Ernst Dating: 29.07.1899
BRIEF OHNE UMSCHLAG Stiasny, Gustav Author: Stiasny, Gustav Recipient: Haeckel, Ernst Dating: 02.07.1901
BRIEF OHNE UMSCHLAG Hold, Alexander Freiherr von Author: Hold, Alexander Freiherr von Recipient: Haeckel, Ernst Dating: 05.05.1900