Submitted on: 03 April 2012.
Revised on: 29 July 2012.
Accepted on: 23 September 2012.
___________________JOURNAL OF MATHEMATICAL CHEMISTRY
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Submitted on: 15 September 2000.
Revised on: 11 October 2000.
Accepted on: 08 December 2000.
___________________JOURNAL OF MATHEMATICAL CHEMISTRY
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