Christensen, E. H., Coombes-Betz, K. M., & Stein, M. S. (2007). The certified quality process analyst handbook. ASQ Quality Press.

Christensen, Eldon H., Kathleen M. Coombes-Betz, and Marilyn S. Stein. The Certified Quality Process Analyst Handbook. Milwaukee, Wisconsin: ASQ Quality Press, 2007.

Christensen, Eldon H., et al. The Certified Quality Process Analyst Handbook. ASQ Quality Press, 2007.