Submitted on: 26 January 2002.
Revised on: 10 March 2002.
Accepted on: 16 March 2002.
MATHEMATICAL MODELS & METHODS IN APPLIED SCIENCES
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Submitted on: 28 July 2012.
Revised on: 08 August 2012.
Accepted on: 02 September 2012.
MATHEMATICAL MODELS & METHODS IN APPLIED SCIENCES
Submitted on: 16 January 2015.
Revised on: 01 February 2015.
Accepted on: 26 February 2015.
MATHEMATICAL MODELS & METHODS IN APPLIED SCIENCES
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Submitted on: 25 January 2015.
Revised on: 04 February 2015.
Accepted on: 13 February 2015.
MATHEMATICAL MODELS & METHODS IN APPLIED SCIENCES
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