Document Type : Research Articles
Authors
1 Department of Mathematics, Faculty of Sciences, University of Gonabad, Gonabad, Iran.
2 Department of Applied Mathematics, Faculty of Mathematical Sciences, Ferdowsi University of Mashhad, Mashhad, Iran.
3 Department of Applied Mathematics, Faculty of Mathematical Sciences, Ferdowsi University of Mashhad, Mashhad, Iran. Mashhad‎, ‎Iran.
Abstract
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