BRIEF [O.A.] Schepotieff, Alexander Author: Schepotieff, Alexander Recipient: Haeckel, Ernst Dating: 01.04.1912
BRIEF [O.A.] Donvito, Eduardo Author: Donvito, Eduardo Recipient: Haeckel, Ernst Corporation: Il Pubblicista - La Gioventù Dating: 02.04.1912
BRIEF [O.A.] Donvito, Eduardo Author: Donvito, Eduardo Recipient: Haeckel, Ernst Corporation: Il Pubblicista - La Gioventù Dating: 04.02.1912
BRIEF [O.A.] Donvito, Eduardo Author: Donvito, Eduardo Recipient: Haeckel, Ernst Corporation: Il Pubblicista - La Gioventù Dating: 26.02.1912