Submitted on: 12 January 1999.
Revised on: 02 April 1999.
Accepted on: 22 April 1999.
___________________APPLIED MATHEMATICAL MODELLING
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Submitted on: 17 March 2017.
Revised on: 03 May 2017.
Accepted on: 27 May 2017.
___________________APPLIED MATHEMATICAL MODELLING
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Submitted on: 08 April 2023.
Revised on: 20 May 2023.
Accepted on: 06 June 2023.
___________________APPLIED MATHEMATICAL MODELLING
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Submitted on: 01 January 2007.
Revised on: 19 April 2007.
Accepted on: 31 May 2007.
___________________APPLIED MATHEMATICAL MODELLING
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