Affiliation: | 1. Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA;2. Faculty of Science, Department of Mathematics, King Abdulaziz University, Jeddah 21589, Saudi Arabia;3. Department of Mathematics, Faculty of Mathematical Sciences, University of Guilan, Rasht, Iran;4. Department of Mathematics, Faculty of Mathematical Sciences, University of Mazandaran, Babolsar, Iran |