BRIEF [O.A.] Haeckel, Charlotte Author: Haeckel, Charlotte Recipient: Haeckel, Ernst Dating: 12.01.1866
BRIEF [O.A.] Haeckel, Charlotte Author: Haeckel, Charlotte Recipient: Haeckel, Ernst Dating: 29.01.1866
BRIEF [O.A.] Kauffmann, Julius Author: Kauffmann, Julius Recipient: Haeckel, Ernst Dating: 18.09.1866