1. Department of Mathematics; Faculty of Science, Cairo University; Giza Egypt
2. Department of Mathematics and Statistics; College of Science, Al-Imam Mohammad Ibn Saud Islamic University (IMSIU); Riyadh Saudi Arabia
3. Department of Mathematics; Faculty of Science, Beni-Suef University; Beni-Suef Egypt
4. Department of Basic Science; Institute of Engineering, Canadian International College (CIC); Giza Egypt
5. Department of Mathematics; Cankaya University; Ankara Turkey
6. Institute of Space Sciences; Magurele-Bucharest Romania