BRIEF [O.A.] Genestoux, Calemard du Author: Genestoux, Calemard du Recipient: Haeckel, Ernst Dating: 27.10.????
BRIEF [O.A.] Giard, Alfred Author: Giard, Alfred Recipient: Haeckel, Ernst Corporation: Sorbonne facultè des Sciences, Laboratoire de Zoologie Maritime de Wimereux (Pas-de Calais) Dating: 02.03.1889
BRIEF [O.A.] Giard, Alfred Author: Giard, Alfred Recipient: Haeckel, Ernst Corporation: Station Zoologique de Wimereux Pas de Calais Dating: 31.08.1901
BRIEF [O.A.] Gsell, Paul Author: Gsell, Paul Recipient: Haeckel, Ernst Corporation: La Revue Dating: 16.08.1903
BRIEF [O.A.] Gsell, Paul Author: Gsell, Paul Recipient: Haeckel, Ernst Corporation: La Revue Dating: 11.09.1905