Institution: | (1) Department of Mathematics, Damietta Faculty of Science, New Damietta, 34517, Egypt;(2) Department of Mathematics, ABHA Teachers’ College, ABHA P.O. Box 429, Abha, Saudi Arabia;(3) Departamento de Matemática Aplicada II, E.T.S.I. Telecomunicación, Campus Marcosende, Universidad de Vigo, 36280 Vigo, Spain |