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Submitted on: 03 February 2011.
Revised on: 01 March 2011.
Accepted on: 10 March 2011.
University Politehnica of Bucharest Scientific Bulletin-Series A-Applied Mathematics and Physics
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Submitted on: 14 July 2023.
Revised on: 21 July 2023.
Accepted on: 06 August 2023.
University Politehnica of Bucharest Scientific Bulletin-Series A-Applied Mathematics and Physics
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Submitted on: 30 September 2009.
Revised on: 20 October 2009.
Accepted on: 14 November 2009.
University Politehnica of Bucharest Scientific Bulletin-Series A-Applied Mathematics and Physics
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