The Appleton-Century mss., 1846-1962, consists of the office files of the publishing company, its two predecessors, D. Appleton & Co., and the Century Co., and to a small extent its successor, Appleton-Century Crofts, Inc.
The Haldeman mss. II, 1908-1951, consists of correspondence of writers and editors, including Emanuel Haldeman-Julius, 1889-1951, who were connected to Haldeman-Julius Publications.
The Haldeman mss. III, 1915-1918, consists primarily of correspondence of Upton Beall Sinclair, 1878-1968, novelist, and Appeal to Reason staff members Louis Kopelin, 1887-1949, and Walter H. Wayland, 1884-1980.
The Boni mss., 1926-1939, consists of the correspondence of author Upton Beall Sinclair, 1878-1968, with publishers Albert Boni, 1892-1981, and Charles Boni, 1894-1969.
The Sinclair mss. VIII, 1939-1998, consist of financial documents, correspondence, and contracts from McIntosh & Otis during their representation of Upton Sinclair and the Sinclair estate through David Sinclair.
The Saturday Review of Literature mss., 1946-1956, consists of letters from author Upton Sinclair, 1878-1968, to Norman Cousins, 1915-1990, and Harrison Smith, 1888-1971, editors of the Saturday Review of Literature.
The Haldeman mss., 1948-1960, consists of files from Haldeman-Julius Publications of Girard, Kansas, containing correspondence with and book sales records of writer Upton Beall Sinclair, 1878-1968.