1. Department of Mathematics, Faculty of Science, Tanta University, Tanta, Egypt
2. Department of Statistics and Operations Research, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
3. College of Vestsjaelland South, Herrestraede 11, 4200 Slagelse, Denmark
4. Department of Physics and Engineering Mathematics, Faculty of Engineering, Kafrelsheikh University, Kafrelsheikh 33516, Egypt
5. Department of Mathematics, Faculty of Science, New Valley University, Egypt