Gibson, William M., "Introduction," in Mark Twain's Mysterious Stranger Manuscripts, edited by William M. Gibson, University of California Press, 1969, pp. 1—34.

Kahn, Sholom, Jr., Mark Twain's Mysterious Stranger: A Study of the Manuscript Texts, University of Missouri Press, 1978, pp. 4—25, 199.

Royal, Derek Parker, "Terrible Dreams of Creative Power: The Question of No. 44," Studies in the Novel, Vol. 31, No. 1, Spring 1999, pp. 44—59.

Twain, Mark, No. 44, The Mysterious Stranger, University of California Press, 2004.