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Submitted on: 24 January 2013.
Revised on: 05 February 2013.
Accepted on: 12 February 2013.
TWMS Journal of Pure and Applied Mathematics
Submitted on: 17 June 1998.
Revised on: 25 July 1998.
Accepted on: 01 August 1998.
TWMS Journal of Pure and Applied Mathematics
Submitted on: 03 September 2005.
Revised on: 29 September 2005.
Accepted on: 09 October 2005.
TWMS Journal of Pure and Applied Mathematics
Submitted on: 07 July 2000.
Revised on: 18 July 2000.
Accepted on: 26 July 2000.
TWMS Journal of Pure and Applied Mathematics
Submitted on: 23 August 2012.
Revised on: 05 September 2012.
Accepted on: 27 September 2012.
TWMS Journal of Pure and Applied Mathematics
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