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2. Liker, J.K. (2004), The Toyota Way: 14 Management Principles from the World's Greatest Manufacturer, McGraw‐Hill Publishing, New York, NY, p. 37.
3. Ohno, T. (1988), Toyota Production System; Beyond Large‐scale Production, Productivity Press, Cambridge, MA, p. 3.
4. Society of Manufacturing Engineers (2001), “Ford embraces six‐sigma quality goals”, available at: www.sme.org/cgi‐bin/get‐press.pl?&&20012513&ND&&SME&.
5. Toyota (2005), “Toyota Traditions: Ask ‘why’ 5 times about every matter”, available at: www.toyota.co.jp/en/vision/traditions/mar_apr_06.html.