Submitted on: 09 June 2004.
Revised on: 07 July 2004.
Accepted on: 18 July 2004.
___________________INTERNATIONAL JOURNAL OF MATHEMATICS AND MATHEMATICAL SCIENCES
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Submitted on: 26 September 2009.
Revised on: 23 January 2010.
Accepted on: 13 March 2010.
___________________INTERNATIONAL JOURNAL OF MATHEMATICS AND MATHEMATICAL SCIENCES
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