BRIEF [O.A.] Ferguson, Campbell Author: Ferguson, Campbell Recipient: Haeckel, Ernst Dating: 10.07.1909
BRIEF OHNE UMSCHLAG Doubleday, H. S. Author: Doubleday, H. S. Recipient: Haeckel, Ernst Dating: 22.03.1909
BRIEF [O.A.] Witton, H... B... Author: Witton, H... B... Recipient: Haeckel, Ernst Dating: 28.10.1909
BRIEF [O.A.] Witton, H... B... Author: Witton, H... B... Recipient: Haeckel, Ernst Dating: 30.09.1909
BRIEF OHNE UMSCHLAG Witton, Henry Buckingham Author: Witton, Henry Buckingham Recipient: Haeckel, Ernst Dating: 08.11.1909