BRIEF [O.A.] Du Bois-Reymond, Emil Author: Du Bois-Reymond, Emil Recipient: Haeckel, Ernst Dating: ??.??.1865
BRIEF OHNE UMSCHLAG Peters, Wilhelm Author: Peters, Wilhelm Recipient: Haeckel, Ernst Dating: 02.02.1865
BRIEF OHNE UMSCHLAG Sethe, Wilhelmine Author: Sethe, Wilhelmine Recipient: Haeckel, Ernst Dating: 10.06.1865
BRIEF OHNE UMSCHLAG Haeckel, Charlotte Auguste Henriette Author: Haeckel, Charlotte Auguste Henriette Recipient: Haeckel, Ernst Dating: 20.02.1865