BRIEF [O.A.] Awramoff, Stephan Author: Awramoff, Stephan Recipient: Haeckel, Ernst Dating: 03.07.1909
BRIEF [O.A.] Aschen, Fr... von Author: Aschen, Fr... von Recipient: Haeckel, Ernst Dating: 07.10.1914
BRIEF [O.A.] Bluth, Else [Dr.] [?] Author: Bluth, Else [Dr.] [?] Recipient: Haeckel, Ernst Dating: 08.09.1909
POSTKARTE Tyrrell Leith, E... Author: Tyrrell Leith, E... Recipient: Haeckel, Ernst Dating: 29.08.1887