Institution: | [1]Department of Physics, Faculty of Science, University of Yaounde I, P.O. Box 812, Cameroon [2]Department of Physics, Higher Teacher's Training College, University of Maroua, P.O. Box 46, Cameroon [3]Ecole Nationale Superieure Polytechnique, University of Yaounde I, P.O. Box 8390, Cameroon |