BRIEF OHNE UMSCHLAG Burbach, Otto Author: Burbach, Otto Recipient: Haeckel, Ernst Corporation: Naturhistorische Sammlungen des Herzoglichen Museums Dating: 31.03.1885
BRIEF OHNE UMSCHLAG Gegenbaur, Carl Author: Gegenbaur, Carl Recipient: Haeckel, Ernst Dating: 26.06.1885
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Charlotte [Mutter] Dating: 23.04.1885
BRIEF OHNE UMSCHLAG Haacke, Wilhelm Author: Haacke, Wilhelm Recipient: Haeckel, Ernst Dating: 25.01.1885