Ogden, p. 178. Frederic D. Ogden, Keen Johnson, in Lowell Hayes Harrison (a cura di), Kentucky's Governors, Lexington, Kentucky, The University Press of Kentucky, 2004, ISBN0-8131-2326-7.
worldcat.org
Powell, p. 96. Robert A. Powell, Kentucky Governors, Danville, Kentucky, Bluegrass Printing Company, 1976, OCLC2690774.