BRIEF [O.A.] Brockhaus, Friedrich Author: Brockhaus, Friedrich Recipient: Haeckel, Ernst Dating: 14.07.1892
BRIEF [O.A.] Brockhaus, Friedrich Author: Brockhaus, Friedrich Recipient: Haeckel, Ernst Dating: 14.07.1892
BRIEF [O.A.] Brockhaus, Friedrich Author: Brockhaus, Friedrich Recipient: Haeckel, Ernst Dating: 26.07.1892
BRIEF [O.A.] Brockhaus, Friedrich Author: Brockhaus, Friedrich Recipient: Haeckel, Ernst Dating: 29.07.1892
BRIEF [O.A.] Brockhaus, Friedrich Author: Brockhaus, Friedrich Recipient: Haeckel, Ernst Dating: 03.08.1892
BRIEF OHNE UMSCHLAG Brockhaus, Friedrich Author: Brockhaus, Friedrich Recipient: Haeckel, Ernst [et al.] Dating: 26.07.1892