BRIEF [O.A.] Cabasino-Renda, G... Author: Cabasino-Renda, G... Recipient: Haeckel, Ernst Corporation: Giornale d'Italia – Rom Dating: 21.02.1911
BRIEF OHNE UMSCHLAG Andreae, Eckart Author: Andreae, Eckart Recipient: Haeckel, Ernst Dating: 15.02.1919
BRIEF OHNE UMSCHLAG Andreae, Eckart Author: Andreae, Eckart Recipient: Haeckel, Ernst Dating: 19.03.1919