Bellamy, Gladys Carmen, "The Humorist as Technician," in Mark Twain as a Literary Artist, University of Oklahoma Press, 1950, p. 123.

DeVoto, Bernard, Mark Twain's America, The Riverside Press, 1951, p. 253.

Emerson, Everett, "A Backward Glance," in The Authentic Mark Twain: A Literary Biography of Samuel L. Clemens, University of Pennsylvania Press, 1984, p. 272.

Horowitz, Floyd R., "'The Invalid's Story': An Early Mark Twain Commentary on Institutional Christianity," in Midcontinent American Studies Journal, Vol. 7, No. 1, 1966, pp. 38-40.

Kemper, Steven E., "Poe, Twain, and Limburger Cheese," in Mark Twain Journal, Vol. XXI, No. 1, Winter 1981-1982, pp. 13-14.

Long, E. Hudson, "Mind and Art," in Mark Twain Handbook, Hendricks House, 1957, p. 341.