Aleksandr Solzhenitsyn, 1973. Three-volume non-fiction testimony of the Soviet camp system.
From Wikipedia
The Gulag Archipelago: An Experiment in Literary Investigation is a three-volume nonfiction series written between 1958 and 1968 by Russian writer Aleksandr Solzhenitsyn, a Soviet dissident. It was first published in 1973 by the Parisian publisher YMCA-Press, and it was translated into English and French the following year. It explores a vision of life in what is often known as the Gulag, the Soviet labour camp system. Solzhenitsyn constructed his highly detailed narrative from various sources including reports, interviews, statements, diaries, legal documents, and his own experience as a Gulag prisoner.