Gilder Lehrman Institute of American History. Archived from the original on August 18, 2016.
Wills, Garry (2012). Lincoln at Gettysburg: The Words that Remade America. New York, New York: Simon and Schuster. ISBN 978-1-4391-2645-5.
Wilson, Douglas Lawson; Davis, Rodney O.; Wilson, Terry; Herndon, William Henry; Weik, Jesse William (1998). Herndon's Informants: Letters, Interviews, and Statements about Abraham Lincoln. Univ of Illinois Press. pp. 35–36. ISBN 978-0-252-02328-6.
Wilson, Douglas L. (1999). Honor's Voice: The Transformation of Abraham Lincoln. New York: A. A. Knopf. ISBN 978-0-307-76581-9.
Winkle, Kenneth J. (2001). The Young Eagle: The Rise of Abraham Lincoln. Lanham, Maryland: Taylor Trade Publishing. ISBN 978-1-4617-3436-9.
Zarefsky, David (1993). Lincoln, Douglas, and Slavery: In the Crucible of Public Debate. Chicago, Illinois: University of Chicago Press. ISBN 978-0-226-97876-5.

