BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Wundt, Wilhelm Dating: 07.06.1875
BRIEF OHNE UMSCHLAG Dodel-Port, Arnold Author: Dodel-Port, Arnold Recipient: Haeckel, Ernst Dating: 07.01.1875
BRIEF [O.A.] Dammer, Otto Author: Dammer, Otto Recipient: Haeckel, Ernst Corporation: Meyers Konversations-Lexikon, Redaktion Dating: 01.03.1875
BRIEF OHNE UMSCHLAG Engelmann, Theodor Wilhelm Author: Engelmann, Theodor Wilhelm Recipient: Haeckel, Ernst Dating: 28.12.1875
BRIEF OHNE UMSCHLAG Deubler, Konrad Author: Deubler, Konrad Recipient: Haeckel, Ernst Dating: 30.01.1875