1. Higher Teacher's Training College, University of Maroua, Maroua, Cameroon
2. Faculty of Sciences, University of Maroua, Maroua, Cameroon
3. The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
4. Department of Physics, College of Arts and Science, Prince Sattam bin Abdulaziz University, Wadi Al-Dawaser, Saudi Arabia
5. Department of Physics, Faculty of Science, Ain Shams University, Cairo, Egypt