1. Department of Mathematics, Faculty of Arts and Sciences, Ondokuz Mayis University, Samsun 55139, Turkey
2. Department of Mathematics, Yarmouk University, Irbid 21163, Jordan
3. Department of Mathematics and Statistics, Central University of Punjab, Bathinda, Punjab 151001, India
4. Instituto Universitario de Matematica Pura y Aplicada, Universitat Politècnica de València, Valencia 46022, Spain