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Submitted on: 29 October 2011.
Revised on: 16 February 2012.
Accepted on: 20 March 2012.
___________________International Journal of Mathematics and Physics
Submitted on: 25 March 1998.
Revised on: 17 July 1998.
Accepted on: 30 August 1998.
___________________International Journal of Mathematics and Physics
Submitted on: 06 June 2014.
Revised on: 02 August 2014.
Accepted on: 15 September 2014.
___________________International Journal of Mathematics and Physics
Submitted on: 07 June 2008.
Revised on: 26 August 2008.
Accepted on: 14 September 2008.
___________________International Journal of Mathematics and Physics
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Submitted on: 21 November 2005.
Revised on: 07 March 2006.
Accepted on: 30 March 2006.
___________________International Journal of Mathematics and Physics
Submitted on: 28 November 2010.
Revised on: 06 March 2011.
Accepted on: 18 March 2011.
___________________International Journal of Mathematics and Physics
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