BRIEF [O.A.] Woltmann, Ludwig Author: Woltmann, Ludwig Recipient: Haeckel, Ernst Dating: 1901.??.?? [Ende]
BRIEF [O.A.] Hildebrand, Adolf von Author: Hildebrand, Adolf von Recipient: Haeckel, Ernst Dating: 18.12.1901
BRIEF [O.A.] Lakowitz, Konrad Author: Lakowitz, Konrad Recipient: Haeckel, Ernst Corporation: Naturforschende Gesellschaft zu Danzig Dating: 22.09.1901
BRIEF OHNE UMSCHLAG Korsch, Carl August Author: Korsch, Carl August Recipient: Haeckel, Ernst Dating: 18.08.1901