BRIEF [O.A.] Eberly, Ralph H... Author: Eberly, Ralph H... Recipient: Haeckel, Ernst Dating: 03.04.1894
BRIEF [O.A.] Recipient: Haeckel, Ernst Corporation: American Philosophical Society Dating: 11.12.1908
BRIEF [O.A.] Smith, Edgar J... Author: Smith, Edgar J... Recipient: Haeckel, Ernst Corporation: American Philosophical Society Dating: 13.12.1905
BRIEF [O.A.] Sonneberg, Walter Author: Sonneberg, Walter Recipient: Haeckel, Ernst Dating: 16.04.1905