BRIEF [O.A.] Sutton, A... R... Author: Sutton, A... R... Recipient: Haeckel, Ernst Dating: 10.06.1892
BRIEF [O.A.] Orr, Henry B... Author: Orr, Henry B... Recipient: Haeckel, Ernst Corporation: Tulane-University Dating: 09.02.1894
BRIEF [O.A.] Orr, Henry B... Author: Orr, Henry B... Recipient: Haeckel, Ernst Corporation: Tulane-University Dating: 08.04.1899