Wonnacott, T. H., & Wonnacott, R. J. (1990). Introductory statistics for business and Economics (4th.ed.). John Wiley & sons.

Wonnacott, Thomas H., and Ronald J. Wonnacott. Introductory Statistics for Business and Economics. 4th.ed. New York: John Wiley & sons, 1990.

Wonnacott, Thomas H., and Ronald J. Wonnacott. Introductory Statistics for Business and Economics. 4th.ed. John Wiley & sons, 1990.