1. Robert S. Kaplan and David P. Norton, The Balanced Scorecard: Translating Strategy into Action, Harvard Business School Press, 1996.
2. M.G. Kendall and W.R. Buckland, A Dictionary of Statistical Terms, Longman Group, 1971, p. 186.
3. This section is adapted in part from Pete Pande and Larry Holpp, What Is Six Sigma?, McGraw-Hill, 2002; Greg Brue, Six Sigma for Managers, McGraw Hill, 2002; and Peter Pande, Robert Neuman, and Roland Cavanagh, The Six Sigma Way Team Fieldbook, McGraw-Hill, 2002.
4. Peter Pande, Robert Neuman, and Roland Cavanagh, The Six Sigma Way Team Fieldbook, McGraw-Hill, 2002, p. 14.