Personal documents; correspondence with his fiancée Thérèse Bognar 1901-1907, after her death in 1907 continued in the form of letters to her with the character of a diary 1907-1921; diaries, handwritten memoirs and notes until 1944; correspondence with many persons and organizations, including Diego Abad de Santillán 1922-1937, Annie Adama van Scheltema 1935-1944, Marussia Bakunin 1898-1913, Alexander Berkman 1908-1936, Eduard Bernstein 1898-1905, Luigi Bertoni 1900-1939, Gustave Brocher 1923-1931, Fritz Brupbacher 1913-1940, Varlaam and Frida Čerkezov 1892-1934, Lilly and Christiaan Cornelissen 1900-1939, Victor Dave 1887-1922, A. Davies 1898-1912, Ferdinand Domela Nieuwenhuis 1896-1913, Stephanus Fabijanovič 1926-1934, Raphael Friedeberg 1933-1939, Emma Goldman 1899-1939, Jean Grave 1897-1934, Jacques Gross 1893-1936, Lucien and Louise Guérineau 1919-1938, James Guillaume 1891-1914, Charles Hotz 1922-1937, Albert de Jong 1923-1933, Thomas H. Keell 1904-1938, Harry M. Kelly 1899-1940, Peter Kropotkin 1892-1913, Gustav Landauer 1893-1919, Arthur Lehning 1924-1936, Errico Malatesta 1889-1932, Alfred and Helen Marsh 1895-1910, Theodor Mauthner 1897-1921, Amélie Mauthner 1923-1929, Elena Melli-Malatesta 1932-1937, Libero and Saverio Merlino 1892-1938, Jacques Mesnil 1897-1940, Louise Michel 1898, Federica Montseny 1927-1940, Siegfried Nacht (Stephen Naft) 1920-1937, Boris Nikolaevskij 1930-1940, Joseph Presburg. (Pseudonym Perry) 1896-1901, Pierre Ramus 1906-1930, Rudolf Rocker 1895-1939, Alfred Sanftleben 1896-1938, Gertrud Schack 1888-1903 , Alexander Schapiro 1907-1930, Augustin Souchy 1923-1937, Paraškev Stojanov 1892-1939, Max Winkler 1922-1933 and Albert Zibelin 1892-1914; files on Elisée Reclus, consisting of his correspondence with Max Nettlau 1878-1904, letters from Paul Reclus 1924-1939 and from Jacques Reclus 1924-1937 to Max Nettlau and other documents; on Peter Kropotkin, consisting of some manuscripts and printer's proofs of Kropotkin's M̀emoirs of a revolutionist', M̀utual aid' and of a study on Russian literature, transcripts of letters from Kropotkin to James Guillaume, Luigi Bertoni, Victor Dave, Paul Robin and others, letters from Fritz Brupbacher, Ferdinand Domela Nieuwenhuis, Saverio Merlino, James Guillaume, Alfred Marsh, Marie Goldsmith, Čerkezov and others to Max Nettlau, concerning Peter Kropotkin 1912, notes, manuscripts; files on Ernest Coeurderoy, Errico Malatesta, Filippo Buonarroti, Joseph Déjacque and others; documentation on anarchist and socialist persons and organizations in Great Britain (Socialist League, Freedom, Fabians), France, Russia, Germany, Belgium, the Netherlands, International Socialist Congresses 1889-1907, etc.; manuscripts of his books and many articles, and of unpublished studies; bibliographical and other notes of his studies; press clippings, leaflets, etc.
