BRIEF [O.A.] Feather, William Author: Feather, William Recipient: Haeckel, Ernst Corporation: The Paine Monument Association Dating: 01.04.1914
BRIEF [O.A.] Baumann, Friedrich Author: Baumann, Friedrich Recipient: Haeckel, Ernst Dating: 28.09.1914
TELEGRAMM Ward, Percy H. Author: Ward, Percy H. Recipient: Haeckel, Ernst Corporation: Chicago Freethought Society Dating: 16.02.1914
BRIEF OHNE UMSCHLAG Ward, Percy H. Author: Ward, Percy H. Recipient: Haeckel, Ernst Dating: 18.02.1914