1. Bond, Guy L. and Miles A. Tinker. Reading Difficulties: Their Diagnosis and Correction. New York: Appleton-Century-Crofts, 1967, p. 448.
2. Harris, Albert J. How to Increase Reading Ability. New York: David McKay Company, Inc., 1970, p.291.
3. Marksheffel, Ned D. Better Reading in the Secondary Schools. Ronald Press Company, 1966, pp. 72–74.