1. Department of Physics, Faculty of Science, University of Maroua, P.O. Box 814, Cameroon
2. Department of Physics, Higher Teachers’ Training College of Maroua, The University of Maroua, P.O. Box 55, Cameroon
3. Department of Life and Earth Sciences, Higher Teachers’ Training College of Maroua, University of Maroua, P.O. Box 55, Cameroon