Book: Baker, Jean H. James Buchanan: The American Presidents Series: The 15th President, 1857-1861. Times Books, 2004.
Book: Curtis, George Ticknore. Life of James Buchanan: Fifteenth President of the United States. Harper & Brothers, 1883.
Book: Klein, Philip S. President James Buchanan: A Biography. American Political Biography Press, 1995.
Book: Nikel, Jim. The First Gay President? A Look into the Life and Sexuality of James Buchanan, Jr. Minute Help Press, 2011.
Buchanan Papers: http://www2.hsp.org/collections/manuscripts/b/Buchanan0091.html