BRIEF [O.A.] Poincaré, Henry Author: Poincaré, Henry Recipient: Haeckel, Ernst Corporation: Institut General Psychologique Dating: 14.11.1910
BRIEF [O.A.] Delines, Michel Author: Delines, Michel Recipient: Haeckel, Ernst Corporation: "Temps" de la "Bibliotheque Universelle" et de "L'Odesski Listok" Dating: 28.06.1910
BRIEF [O.A.] Grignoux, A... Le Author: Grignoux, A... Le Recipient: Haeckel, Ernst Dating: 28.02.1910
BRIEF [O.A.] Mayer, Louis Author: Mayer, Louis Recipient: Haeckel, Ernst Corporation: Institut Océanographique Dating: 07.01.1910