Personal papers: identity cards, certificates and other personal documents 1873-1942 (1943); correspondence with Lilly Rupertus 1906-1914 (-1937), Fred Cornelissen 1907-1917, 1930-1937 and other relatives; correspondence with P. Argyriades 1894-1898, E. Baud 1902, 1907-1909, Fernand Brouez [1893], 1895, Ferdinand Domela Nieuwenhuis 1891, 1899, A. Hamon 1897, 1900 and n.d., Bernard Kampffmeyer 1895, Peter Kropotkin 1895-1896, Bernard Lazare 1895-1896, H.W. Lee 1894-1895, Max Nettlau 1905-1912, 1922, Georges Renard 1894 and others; texts of speeches by Christiaan Cornelissen [1892-1898]; manuscripts of his `Introduction à une sociologie générale' and of his memoirs and parts of some other manuscripts; notes [1886-1899]; copies of his own publications most of them provided with notes and corrections [1891-] 1892-1935, 1944; other documentation 1777-1942 (-1951). Papers of relatives: correspondence by Lilly Rupertus, Fred Cornelissen and other relatives with Freija Benisch, Frida Čerkezov-Rupertus, Henri and Frania Fuss, Arnold van Gennep, Emma Goldman, Jean Grave, Mabel Grave-Holland, Louise Guérinau, Pierra Kropotkine, Marc and E. Pierrot, Jacques Reclus, Paul Reclus and others 1905-1940 (-1948); documents from Fred Cornelissen and his daughter-in-law Nora Cornelissen-Bjune (1906-) 1927-1955.