POSTKARTE Osborn, Henry Fairfield Author: Osborn, Henry Fairfield Recipient: Haeckel, Ernst Dating: ??.??.1906
BRIEF [O.A.] Gregory, William K... Author: Gregory, William K... Recipient: Haeckel, Ernst Corporation: American Museum of Natural History Dating: 23.01.1914
BRIEF [O.A.] Gould, E... F... Author: Gould, E... F... Recipient: Haeckel, Ernst Corporation: Chester & Gould, Physicians and Surgeons Dating: 12.02.1900
BRIEF [O.A.] George, G... K... Author: George, G... K... Recipient: Haeckel, Ernst Corporation: G. K. George Dating: 11.03.1907
BRIEF [O.A.] Gurley, Ralph Randolph Author: Gurley, Ralph Randolph Recipient: Haeckel, Ernst Dating: 08.02.1909