-Modern Mathematics with Applications to Business and the Social Sciences, by Ruric E. Wheeler and W. D. Peeples, Jr., 4th ed., Monterey, Calif., Brooks/Cole Publishing Company, 1986
-Basic Business Statistics: Concepts and Applications, by Mark L. Berenson, David M. Levine, and Timothy C. Krehbiel, 11th ed., Prentice Hall, 2008