Submitted on: 21 March 1999.
Revised on: 11 May 1999.
Accepted on: 30 May 1999.
___________________Eurasian Business Review---SPRINGER HEIDELBERG
Submitted on: 10 July 2012.
Revised on: 09 August 2012.
Accepted on: 27 August 2012.
___________________Eurasian Business Review---SPRINGER HEIDELBERG
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Submitted on: 14 July 2013.
Revised on: 25 August 2013.
Accepted on: 14 September 2013.
___________________Eurasian Business Review---SPRINGER HEIDELBERG
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