1. Geodesy Research Laboratory, National Institute of Cartography, Yaoundé, Cameroon
2. Department of Physics, University of Yaoundé 1, Yaoundé, Cameroon
3. Department of Geophysics, Faculty of Physics, University of Science, Vietnam National University, Ha Noi, Vietnam
4. Department of Land Surveying and Geo-Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong
5. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires (IGeBA), CONICET – Universidad de Buenos Aires, Buenos Aires, Argentina
6. Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Buenos Aires, Buenos Aires, Argentina
7. Faculty of Geology, University of Science, Vietnam National University, Ha Noi, Vietnam