BRIEF [O.A.] Camerano, Lorenzo Author: Camerano, Lorenzo Recipient: Haeckel, Ernst Dating: 28.05.1900
BRIEF [O.A.] Moriondo, Luigi Author: Moriondo, Luigi Recipient: Haeckel, Ernst Corporation: Società Anonima, L`Unione Tipografico-Editrice, Torinese Dating: 19.01.1900
BRIEF [O.A.] Moriondo, Luigi Author: Moriondo, Luigi Recipient: Haeckel, Ernst Corporation: Società Anonima, L`Unione Tipografico-Editrice, Torinese Dating: 09.04.1900