1. Faculty of Science, Mathematics Dept., Tanta Univ., Tanta 31527, Egypt; and Faculty of Science and Education, Mathematics Dept., Taif Univ. (Al-Khurmah Branch), Kingdom of Saudi Arabia (corresponding author).
2. Faculty of Science, Mathematics Dept., Tanta Univ., Tanta 31527, Egypt; and P.O. Box 5555 Makkah, Kingdom of Saudi Arabia.
3. Faculty of Science, Mathematics Dept., Minufiya Univ., Shebin El-Koum, Egypt.