Gerrit Achterberg Collection of the poet Gerrit Achterberg (1905-1962) Willem Bilderdijk The author, lawyer, historian, translator and poet Willem Bilderdijk (1756-1831) P.C. Boutens Works by the poet P.C. Boutens (1870-1943) Cornets de Groot The Cornets-De Groot family archive contains documents related to Hugo de Groot and the (Cornets) De Groot family Couperus The KB c.2,000 books by Couperus and has a copy of virtually all editions of his works Jacob Jan Cremer De collection manuscripts of writer Jacob Jan Cremer (1827-1880) Gijsbert Cuper The papers of Gijsbert Cuper (1644-1716), professor of classical languages and rector Constantijn Huygens The Huygens collection comprises the literary estate of Constantijn Huygens (1596-1687) and his descendants. E. du Perron Works by writer E. du Perron (1899-1940) and copies of periodicals that he contributed to Willem Kloos About 1.000 books on Willem Kloos en the archive of 'De nieuwe gids' Koopman The collection consists of c. 10.000 volumes of French literary works in special editions Hendrik Marsman The correspondence, proofs, annotated books, offprints and reviews of the work of the Dutch poet Hendrik Marsman (1899-1940) Jacques Perk The manuscripts of and concerning Jacques Perk (1859-1881) contain variant versions of his work Willem Pijper Willem Pijper (1894-1947) was a composer, conductor and publicist Fokke Sierksma The archive of the theologian, essay writer and poet Fokke Sierksma (1917-1977) Jan Te Winkel The archive of the professor of Dutch literature Jan te Winkel (1847-1927) H.F. Tollens Manuscripts, letters and special copies of printed works of the poet H.F. Tollens Cz. (1780-1856) Johannes Theodoor (Jan) Toorop In 1929 the KB acquired the archive of the painter Johannes Theodoor Toorop (1858-1928) Willem Witsen Collection of letters written to the painter, etcher, photographer and publicist Willem Witsen (1860-1923).