Submitted on: 29 February 2004.
Revised on: 27 April 2004.
Accepted on: 16 June 2004.
___________________ECOLOGICAL ECONOMICS---ELSEVIER
Submitted on: 24 August 2004.
Revised on: 22 November 2004.
Accepted on: 07 December 2004.
___________________ECOLOGICAL ECONOMICS---ELSEVIER
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Submitted on: 20 August 2019.
Revised on: 14 October 2019.
Accepted on: 21 November 2019.
___________________ECOLOGICAL ECONOMICS---ELSEVIER
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