(en) Michael Burlingame (dir.), An Oral History of Abraham Lincoln : John G. Nicolay's Interviews and Essays, Carbondale, IL, Southern Illinois University Press, , 167 p. (ISBN978-0-8093-2684-6, lire en ligne), p. 16
(en) Joseph Wallace, Past and Present of the City of Springfield and Sangamon County Illinois, Chicago, S. J. Clarke Publishing Co., (lire en ligne), p. 1477