Submitted on: 13 June 2001.
Revised on: 16 July 2001.
Accepted on: 15 August 2001.
___________________Advances in Applied Mathematics and Mechanics
Submitted on: 23 December 2020.
Revised on: 13 January 2021.
Accepted on: 12 March 2021.
___________________Advances in Applied Mathematics and Mechanics
Submitted on: 19 May 2010.
Revised on: 30 August 2010.
Accepted on: 22 September 2010.
___________________Advances in Applied Mathematics and Mechanics
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Submitted on: 12 May 2010.
Revised on: 25 August 2010.
Accepted on: 11 October 2010.
___________________Advances in Applied Mathematics and Mechanics
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