The Clark mss., 1909-1957, consists of the letters and writings of author, editor, and publisher Thomas Curtis Clark, 1877-1953, as well as the autographs and poems of other writers collected by him.
The Howatt mss., 1902-1959, consist in the main of letters to David Howatt, 1882-1964 , farmer and secretary of Upton Beall Sinclair, from writers Harry Kemp, Upton Beall Sinclair, and William James Durant.
The Munsey mss., 1911-1942, consist of correspondence between The Frank A. Munsey Co., publishers in New York City, and seven authors or their agents concerning publication rights and in some instances film rights.
The Stone mss., 1888-1965, are the papers of Meta (Fuller) Stone. They consist of her writings, including an autobioraphical novel and poetry, and her correspondence with her friends and with her (ex-)husband Upton Beall Sinclair, 1908-1917, much of it concerned with her divorce.