1. Department of Mathematics, Texas A&M University-Kingsville, Kingsville, USA
2. Department of Mathematical Sciences, Faculty of Applied Sciences, Umm Al–Qura University, 21955 Makkah, Saudi Arabia
3. Department of Mathematics, Ecole Normal Supérieur of Mostaganem, 27000 Mostaganem, Algeria; Dipartimento di Matematica e Informatica, Università di Catania, 95125 Catania, Italy
4. Dipartimento di Matematica e Informatica, Università di Catania, 95125 Catania, Italy; Faculty of Fundamental Science, Industrial University of Ho Chi Minh City No. 12 Nguyen Van Bao, Ward 4, Go Vap District, Ho Chi Minh City, Vietnam