BRIEF [O.A.] Kellogg, Vernon Lyman Author: Kellogg, Vernon Lyman Recipient: Haeckel, Ernst Dating: 22.11.1908
BRIEF OHNE UMSCHLAG Benedikt, Moritz Author: Benedikt, Moritz Recipient: Haeckel, Ernst Dating: 28.01.1918
BRIEF OHNE UMSCHLAG Benedikt, Moritz Author: Benedikt, Moritz Recipient: Haeckel, Ernst Dating: 31.01.1918
BRIEF [O.A.] Beneke-Schröer, A... Author: Beneke-Schröer, A... Recipient: Haeckel, Ernst Dating: 12.12.1909
BRIEF OHNE UMSCHLAG Benignus, Wilhelm Author: Benignus, Wilhelm Recipient: Haeckel, Ernst Dating: 31.05.1915
BRIEF OHNE UMSCHLAG Benignus, Wilhelm Author: Benignus, Wilhelm Recipient: Haeckel, Ernst Dating: 12.07.1915