1. Department of Differential Equations, Faculty of Mathematics and Informatics, University of Sofia, Sofia, Bulgaria
2. Department of Mathematics, College of Sciences and Arts, Qassim, University, Ar-Rass, Saudi Arabia
3. Laboratoire de Mathématiques Appliquées, et de Modélisation, Université 8 Mai 1945 Guelma, Guelma 24000, Algeria
4. Applied College, Imam Abdulrahman Bin Faisal, University, Dammam, Saudi Arabia