Submitted on: 17 April 2011.
Revised on: 30 May 2011.
Accepted on: 18 July 2011.
___________________JOURNAL OF ALGEBRA AND ITS APPLICATIONS
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Submitted on: 16 March 2016.
Revised on: 23 June 2016.
Accepted on: 19 August 2016.
___________________JOURNAL OF ALGEBRA AND ITS APPLICATIONS
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http://reply.papertrans.cn/2/152/15196/15196-35.png
Submitted on: 12 December 2009.
Revised on: 07 April 2010.
Accepted on: 30 May 2010.
___________________JOURNAL OF ALGEBRA AND ITS APPLICATIONS