1. Department of MathematicsNational Institute of Technology Jamshedpur India
2. Department of Mathematics, College of Arts and SciencePrince Sattam bin Abdulaziz University Wadi Aldawaser Saudi Arabia
3. Engineering School (DEIM)University of Tuscia Viterbo Italy
4. Department of MathematicsCollege of Science, King Saud University P.O. Box 2455 Riyadh 11451 Saudi Arabia