1. Department of Marine Engineering, Limbe Nautical Arts and Fisheries Institute, P. O. Box 485 Limbe, Cameroon
2. Department of Physics, Faculty of Science, The University of Maroua, P. O. Box 814, Cameroon
3. Higher Teachers’ Training College of Maroua, The University of Maroua, P. O. Box 55, Cameroon
4. Department of Physics, Faculty of Science, The University of Ngaoundere, P. O. Box 454, Cameroon
5. Department of Physics, Faculty of Science, The University of Yaounde I, P. O. Box 812, Cameroon