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Submitted on: 18 March 2002.
Revised on: 10 June 2002.
Accepted on: 31 July 2002.
___________________Advances in Applied Mathematics and Mechanics
Submitted on: 04 July 2006.
Revised on: 23 October 2006.
Accepted on: 12 December 2006.
___________________Advances in Applied Mathematics and Mechanics
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Submitted on: 25 December 2005.
Revised on: 25 March 2006.
Accepted on: 14 April 2006.
___________________Advances in Applied Mathematics and Mechanics
Submitted on: 26 October 2013.
Revised on: 20 February 2014.
Accepted on: 10 April 2014.
___________________Advances in Applied Mathematics and Mechanics
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