1. School of Physical Sciences and Mathematics, Faculty of Exact and Natural Sciences, Pontifical Catholic University of Ecuador, Av. 12 de Octubre 1076 y Roca, Apartado, Quito 17-01-2184, Ecuador
2. Department of Mathematics, College of Science, Jazan University, P.O. Box. 114, Jazan 45142, Saudi Arabia
3. Department of Mathematics, University of Sargodha, Sargodha 40100, Pakistan
4. Department of Mathematics, Government College University, Faisalabad 38000, Pakistan