August Strindberg (1849-1912) is Sweden's most renowned author. His work spans from novels, plays, poetry and essays to photographic works and paintings.
When Strindberg died the National Library was not interested in documenting modern literature. His literary estate, the so called green sack, was therefore given to the Nordic Museum. In 1922, however, the library changed its view and the material was transferred to the National Library.
Since then collection has expanded by means of acquisitions and donations and is the largest collection of Strindberg material.
More on Strindberg on Wikipedia