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Submitted on: 29 June 2017.
Revised on: 07 September 2017.
Accepted on: 21 September 2017.
___________________Journal of Economics---SPRINGER WIEN
Submitted on: 27 December 2001.
Revised on: 05 April 2002.
Accepted on: 04 June 2002.
___________________Journal of Economics---SPRINGER WIEN
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