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Submitted on: 30 May 2011.
Revised on: 22 June 2011.
Accepted on: 19 August 2011.
___________________Journal of Applied Mathematics and Computing
Submitted on: 19 February 2006.
Revised on: 14 March 2006.
Accepted on: 10 May 2006.
___________________Journal of Applied Mathematics and Computing
Submitted on: 20 February 2004.
Revised on: 28 April 2004.
Accepted on: 29 May 2004.
___________________Journal of Applied Mathematics and Computing
Submitted on: 30 January 2005.
Revised on: 27 May 2005.
Accepted on: 24 July 2005.
___________________Journal of Applied Mathematics and Computing