BRIEF [O.A.] Dallmann, Friedr... Author: Dallmann, Friedr... Recipient: Haeckel, Ernst Dating: 15.02.1904
BRIEF [O.A.] Vorpahl, Katharina Author: Vorpahl, Katharina Recipient: Haeckel, Ernst Dating: 15.02.1904
BRIEF [O.A.] Vogtherr, E... Author: Vogtherr, E... Recipient: Haeckel, Ernst Corporation: Bund freier religiöser Gemeinden Deutschlands Dating: 18.12.1904
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Ernst Dating: 12.09.1904