BRIEF [O.A.] Dallmann, Friedr... Author: Dallmann, Friedr... Recipient: Haeckel, Ernst Dating: 15.02.1904
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Ernst Dating: 12.09.1904
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Ernst Dating: 19.10.1904
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Ernst Dating: 15.06.1904
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Ernst Dating: 13.02.1904
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Ernst Dating: 31.01.1904
BRIEF [O.A.] Vorpahl, Katharina Author: Vorpahl, Katharina Recipient: Haeckel, Ernst Dating: 15.02.1904