BRIEF [O.A.] Drugievic, Ferdinand Author: Drugievic, Ferdinand Recipient: Haeckel, Ernst Dating: 13.01.1906
BRIEF [O.A.] Drugievic, Ferdinand Author: Drugievic, Ferdinand Recipient: Haeckel, Ernst Dating: 11.02.1907
BRIEF [O.A.] Dumont, Emerich Baron Author: Dumont, Emerich Baron Recipient: Haeckel, Ernst Dating: 25.06.1876
BRIEF [O.A.] Dumont, Emerich Baron Author: Dumont, Emerich Baron Recipient: Haeckel, Ernst Dating: 26.12.1878
BRIEF [O.A.] Rullmann, Wilhelm Author: Rullmann, Wilhelm Recipient: Haeckel, Ernst Corporation: Grazer "Concordia" Dating: 03.11.1901