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Submitted on: 23 March 2008.
Revised on: 20 May 2008.
Accepted on: 12 July 2008.
___________________ECONOMIST-NETHERLANDS---SPRINGER
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Submitted on: 25 October 2019.
Revised on: 25 November 2019.
Accepted on: 06 December 2019.
___________________ECONOMIST-NETHERLANDS---SPRINGER
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Submitted on: 08 February 2023.
Revised on: 18 March 2023.
Accepted on: 29 April 2023.
___________________ECONOMIST-NETHERLANDS---SPRINGER
http://reply.papertrans.cn/1/80/7988/7988-27.png
Submitted on: 02 May 2001.
Revised on: 07 June 2001.
Accepted on: 05 August 2001.
___________________ECONOMIST-NETHERLANDS---SPRINGER
Submitted on: 05 July 2006.
Revised on: 18 September 2006.
Accepted on: 01 November 2006.
___________________ECONOMIST-NETHERLANDS---SPRINGER
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