BRIEF [O.A.] Frisch Author: Frisch Recipient: Haeckel, Ernst Corporation: Der Floh Dating: 04.11.1907
BRIEF OHNE UMSCHLAG Eggeling, Heinrich von Author: Eggeling, Heinrich von Recipient: Haeckel, Ernst Dating: 02.09.1907
TELEGRAMM Wettstein, Richard von Author: Wettstein, Richard von Recipient: Haeckel, Ernst Corporation: K. K. Zoologisch-Botanische Gesellschaft in Wien Dating: 07.03.1907
BRIEF [O.A.] Drugievic, Ferdinand Author: Drugievic, Ferdinand Recipient: Haeckel, Ernst Dating: 11.02.1907
BRIEF [O.A.] Daxenbichler, Fanny Author: Daxenbichler, Fanny Recipient: Haeckel, Ernst Dating: 14.02.1907
BRIEF [O.A.] Daxenbichler, Fanny Author: Daxenbichler, Fanny Recipient: Haeckel, Ernst Dating: 16.05.1907