BRIEF [O.A.] Littrow, Leontine von Author: Littrow, Leontine von Recipient: Haeckel, Ernst Dating: 24.04.1895
BRIEF [O.A.] Littrow, Heinrich von Author: Littrow, Heinrich von Recipient: Haeckel, Ernst Dating: 01.03.1894
TELEGRAMM Rémy-Berzenkovich von Szillás, Emil Otto Author: Rémy-Berzenkovich von Szillás, Emil Otto Recipient: Haeckel, Ernst Dating: 02.03.1914