BRIEF OHNE UMSCHLAG Suter, Karl Friedrich Author: Suter, Karl Friedrich Recipient: Haeckel, Ernst Dating: 10.10.1901
BRIEF OHNE UMSCHLAG Kraigher-Porges, Josepha Author: Kraigher-Porges, Josepha Recipient: Haeckel, Ernst Dating: 18.12.1901
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rottenburg, Paul von Dating: 16.10.1901