1. Department of Civil Engineering, Advanced Teacher Training College of the Technical Education, University of Douala, Douala, Cameroon
2. Department of Civil Engineering, National Advanced Polytechnical School of Douala, University of Douala, Douala, Cameroon
3. Department of Civil Engineering, National Advanced School of Public Work of Yaoundé, The University of Yaoundé 1, Yaoundé, Cameroon