The Sinclair mss. IV, 1900-1963, consists of correspondence, writings, and monetary statements of author Upton Beall Sinclair, 1878-1968, and of his wife, Mary Craig (Kimbrough) Sinclair, 1883-1961.
The Sinclair mss. V, 1902, consists of the application of novelist Upton Beall Sinclair, 1878-1968, for a fellowship in the Graduate School of Harvard University for the year 1902-1903.
The Sinclair mss. VI, 1907-1977, consists of correspondence, writings, and miscellaneous papers by and relating to author Upton Beall Sinclair, 1878-1968, his wife Mary Craig (Kimbrough) Sinclair, 1882-1961, and his son David Sinclair, 1901-1987.