Submitted on: 16 April 2013.
Revised on: 04 August 2013.
Accepted on: 01 October 2013.
___________________Journal of Mathematical Extension
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Submitted on: 23 May 2008.
Revised on: 21 June 2008.
Accepted on: 17 August 2008.
___________________Journal of Mathematical Extension
Submitted on: 26 April 2012.
Revised on: 04 August 2012.
Accepted on: 27 August 2012.
___________________Journal of Mathematical Extension
Submitted on: 18 October 2014.
Revised on: 10 February 2015.
Accepted on: 22 February 2015.
___________________Journal of Mathematical Extension
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