BRIEF [O.A.] Schorn, Antonie von Author: Schorn, Antonie von Recipient: Haeckel, Ernst Dating: 20.12.1904
BRIEF [O.A.] Stubenrauch, Max von Author: Stubenrauch, Max von Recipient: Haeckel, Ernst Dating: 15.02.1904
BRIEF [O.A.] Molenaar, Heinrich Author: Molenaar, Heinrich Recipient: Haeckel, Ernst Corporation: Sekretariat der dt-franz. Liga Dating: 04.12.1904