Submitted on: 13 December 2010.
Revised on: 03 April 2011.
Accepted on: 20 April 2011.
___________________European Journal of Industrial Engineering
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Submitted on: 19 November 2000.
Revised on: 20 December 2000.
Accepted on: 03 January 2001.
___________________European Journal of Industrial Engineering
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Submitted on: 05 August 2010.
Revised on: 28 September 2010.
Accepted on: 20 November 2010.
___________________European Journal of Industrial Engineering