BRIEF [O.A.] Friedmann, Hermann Author: Friedmann, Hermann Recipient: Haeckel, Ernst Dating: 20.01.1901
BRIEF [O.A.] Friedmann, Hermann Author: Friedmann, Hermann Recipient: Haeckel, Ernst Dating: 15.04.1901
BRIEF OHNE UMSCHLAG Friedmann, Hermann Author: Friedmann, Hermann Recipient: Haeckel, Ernst Dating: 19.04.1901
BRIEF OHNE UMSCHLAG Friedmann, Hermann Author: Friedmann, Hermann Recipient: Haeckel, Ernst Dating: 11.06.1901
BRIEF OHNE UMSCHLAG Friedmann, Hermann Author: Friedmann, Hermann Recipient: Haeckel, Ernst Dating: 03.09.1901
BRIEF OHNE UMSCHLAG Friedmann, Hermann Author: Friedmann, Hermann Recipient: Haeckel, Ernst Dating: 25.09.1901