BRIEF [O.A.] Cless, Alfred Martin Author: Cless, Alfred Martin Recipient: Haeckel, Ernst Dating: 24.03.1900
BRIEF [O.A.] Sevey, Ellen J... Author: Sevey, Ellen J... Recipient: Haeckel, Ernst Dating: 29.??.1900
BRIEF [O.A.] Heath, Harold Author: Heath, Harold Recipient: Haeckel, Ernst Corporation: Leland Stanford Junior University, Department of Zoology Dating: 12.03.1900