1. Alwan, L. C. (2000).Statistical Process Analysis.McGraw-Hill International Edition.
2. Shewhart, W. (1931).Economic Control of Quality Manufactured Product, D. Van Nostrand, New York; reprinted by the American Society for Quality Control in 1980, Milwauker, WI.
3. Shewhart, W. (1939).Statistical Method from the Viewpoint of Quality Control (Graduate School Department of Agriculture,Washington, D. C., reprinted by Dover publication in 1986, Mineola, NY.