1. Cynthia K. Belt and Ray D. Peterson, “Six Sigma Methodology for Improved Energy Efficiency and Productivity,” Light Metals 2007, Vol. 5, ed. M. Sorlie (Warrendale, PA: TMS, 2007), pp. 1141–1146.
2. Cynthia K. Belt and Ray D. Peterson, “Analysis of Energy Efficiency for Industrial Processes,” EPD Congress 2008, ed. S. Howard (Warrendale, PA: TMS, 2008), pp. 53–60.