BRIEF [O.A.] Vranelli, G... Author: Vranelli, G... Recipient: Haeckel, Ernst Corporation: Ministero dell'Istruzione Dating: 20.03.1892
BRIEF [O.A.] Peretti, Vincenzo Author: Peretti, Vincenzo Recipient: Haeckel, Ernst Dating: 27.05.1902
BRIEF [O.A.] Prato, Christofero Author: Prato, Christofero Recipient: Haeckel, Ernst Dating: 09.02.1906
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 28.12.1883
BRIEF [O.A.] Paix Séailles, Ch... Author: Paix Séailles, Ch... Recipient: Haeckel, Ernst Corporation: Le Courrier Européen Dating: 24.12.1904
BRIEF [O.A.] Reggroin, Antonio Author: Reggroin, Antonio Recipient: Haeckel, Ernst Corporation: Zeitschrift "Il Rogo" Dating: 07.11.1911