BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Charlotte Dating: 13.04.1873
BRIEF [O.A.] Georgionpoulos, S... Author: Georgionpoulos, S... Recipient: Haeckel, Ernst Dating: 10.11.1906
BRIEF [O.A.] Ornstein, Bernhard Author: Ornstein, Bernhard Recipient: Haeckel, Ernst Dating: 26.11.1876