1. Draper, N. R. and Smith, H. (1981).Applied Regression Analysis, 2nd ed. John Wiley & Sons, New York, NY, pp. 241–247.
2. Duncan, A. J. (1986).Quality Control and Industrial Statistics, 5th ed. Richard D. Irwin, Homewood, IL, pp. 504.
3. Process Capability Indices
4. Standardization of Shewhart Control Charts