BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 03.03.1866
BRIEF [O.A.] Focke, Gustav Waldemar Author: Focke, Gustav Waldemar Recipient: Haeckel, Ernst Dating: 16.07.1866
BRIEF [O.A.] Focke, Gustav Waldemar Author: Focke, Gustav Waldemar Recipient: Haeckel, Ernst Dating: 11.08.1866
BRIEF [O.A.] Gildemeister, E... Author: Gildemeister, E... Recipient: Haeckel, Ernst Dating: 02.04.1866
BRIEF [O.A.] Romberg, Heinrich Author: Romberg, Heinrich Recipient: Haeckel, Ernst Dating: 01.04.1866