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Submitted on: 25 February 2006.
Revised on: 17 March 2006.
Accepted on: 17 April 2006.
___________________East Asian Journal on Applied Mathematics
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Submitted on: 26 April 2014.
Revised on: 09 June 2014.
Accepted on: 04 August 2014.
___________________East Asian Journal on Applied Mathematics
Submitted on: 20 May 2012.
Revised on: 01 September 2012.
Accepted on: 15 October 2012.
___________________East Asian Journal on Applied Mathematics
Submitted on: 07 November 2004.
Revised on: 27 January 2005.
Accepted on: 09 March 2005.
___________________East Asian Journal on Applied Mathematics
Submitted on: 19 June 2008.
Revised on: 23 September 2008.
Accepted on: 18 October 2008.
___________________East Asian Journal on Applied Mathematics
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