BRIEF [O.A.] Georgionpoulos, S... Author: Georgionpoulos, S... Recipient: Haeckel, Ernst Dating: 10.11.1906
BRIEF [O.A.] Délyanny, Théodore Author: Délyanny, Théodore Recipient: Haeckel, Ernst Dating: 21.06.1896
BRIEF [O.A.] Ornstein, Bernhard Author: Ornstein, Bernhard Recipient: Haeckel, Ernst Dating: 26.11.1876
BRIEF [O.A.] Ornstein, Bernhard Author: Ornstein, Bernhard Recipient: Haeckel, Ernst Dating: 23.08.1879
BRIEF [O.A.] Ornstein, Bernhard Author: Ornstein, Bernhard Recipient: Haeckel, Ernst Dating: 30.12.1876
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Ernst Dating: 08.04.1891