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 Harris, L. mss. consists of materials related to the writing and publication of Upton Sinclair, American Rebel (Crowell, 1975), by author Leon A. Harris, 1926-2000.