Submitted on: 05 April 2012.
Revised on: 10 June 2012.
Accepted on: 24 June 2012.
___________________Applied Mathematics Letters---PERGAMON-ELSEVIER SCIENCE LTD
Submitted on: 25 June 2005.
Revised on: 24 September 2005.
Accepted on: 14 November 2005.
___________________Applied Mathematics Letters---PERGAMON-ELSEVIER SCIENCE LTD
Submitted on: 09 July 2024.
Revised on: 11 October 2024.
Accepted on: 09 November 2024.
___________________Applied Mathematics Letters---PERGAMON-ELSEVIER SCIENCE LTD
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Submitted on: 29 January 2021.
Revised on: 16 April 2021.
Accepted on: 04 May 2021.
___________________Applied Mathematics Letters---PERGAMON-ELSEVIER SCIENCE LTD
Submitted on: 11 November 2006.
Revised on: 13 January 2007.
Accepted on: 09 March 2007.
___________________Applied Mathematics Letters---PERGAMON-ELSEVIER SCIENCE LTD
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