Submitted on: 24 March 2013.
Revised on: 23 May 2013.
Accepted on: 13 June 2013.
___________________Communications in Mathematics and Applications
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Submitted on: 10 June 2020.
Revised on: 12 July 2020.
Accepted on: 29 August 2020.
___________________Communications in Mathematics and Applications
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Submitted on: 31 August 2017.
Revised on: 22 September 2017.
Accepted on: 16 October 2017.
___________________Communications in Mathematics and Applications
Submitted on: 27 April 2023.
Revised on: 01 August 2023.
Accepted on: 23 September 2023.
___________________Communications in Mathematics and Applications
Submitted on: 07 August 2004.
Revised on: 01 September 2004.
Accepted on: 26 October 2004.
___________________Communications in Mathematics and Applications
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Submitted on: 27 July 2022.
Revised on: 08 October 2022.
Accepted on: 19 October 2022.
___________________Communications in Mathematics and Applications
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