Kumar, V., Aaker, D. A., & Day, G. S. (2002). Essentials of marketing research (2nd ed.). Wiley.

Kumar, V., David A. Aaker, and George S. Day. Essentials of Marketing Research. 2nd ed. New York: Wiley, 2002.

Kumar, V., et al. Essentials of Marketing Research. 2nd ed. Wiley, 2002.