1. Rabha M El-Ashwah:
Mathematics Department, Faculty of Science, Mansoura University, New Damietta 34517, Egypt
2. Mohamed K Aouf:
Mathematics Department, Faculty of Science, Mansoura University, Mansoura 33516, Egypt
3. Ali Shamandy:
Mathematics Department, Faculty of Science, Mansoura University, Mansoura 33516, Egypt
4. Sheza M El-Deeb:
Mathematics Department, Faculty of Science, Mansoura University, New Damietta 34517, Egypt