BRIEF [O.A.] Hepner, Adolf Author: Hepner, Adolf Recipient: Haeckel, Ernst Corporation: Abend "Anzeiger", Office of Dating: 27.03.1903
BRIEF OHNE UMSCHLAG Martin, Clarence Author: Martin, Clarence Recipient: Haeckel, Ernst Corporation: The Urologic & Cutaneous Review Dating: 19.05.1914
BRIEF [O.A.] Hempel, Max Author: Hempel, Max Recipient: Haeckel, Ernst Corporation: Bund der Freien Gemeinden und Freidenker-Vereine von Nord-Amerika Dating: 18.06.1904
BRIEF [O.A.] Eldredge, Charles F... Author: Eldredge, Charles F... Recipient: Haeckel, Ernst Corporation: Office of The Philosopher Dating: 14.04.1902
BRIEF OHNE UMSCHLAG Amerland, William H. Author: Amerland, William H. Recipient: Haeckel, Ernst Corporation: A. Leschen & Sons Rope Co. Dating: 26.05.1910