1. Chakravorty, S.S.: Six Sigma programs: an implementation model. Int. J. Prod. Econ. 119, 1–16 (2009)
2. Cox, R.F., Issa, R.R., Ahrens, D.: Management’s perception of key performance indicators for construction. J. Constr. Eng. Manage. 129(2), 142–151 (2003)
3. Creveling, C.M., Hambleton, L., McCarthy, B.: Six Sigma for Marketing Processes: An Overview for Marketing Executives, Leaders and Managers. Pearson Education, Boston (2006)
4. General Electric: General Electric Company 1997 Annual Report (1997).
5. Hahn, G.J., Doganaksoy, N., Hoerl, R.W.: The evolution of Six Sigma. Qual. Eng. 12(3), 317–326 (2000)