1. Faculty of Science, Department of Inorganic Chemistry, Laboratory of Applied Inorganic Chemistry, University of Yaounde I, Yaounde, Cameroon
2. Institut für Mineralogie, Leibniz Universität Hannover, Hannover, Germany
3. Department of Chemistry in Higher Teacher Training College, University of Maroua, Maroua, Cameroon
4. Local Materials Promotion Authority, Yaoundé, Cameroon
5. Department of Engineering Enzo Ferrari, University of Modena and Reggio Emilia, Modena, Italy