[1] Univ NDjamena, Fac Econ & Management, Lab Anal & Res Math Econ, Ndjamena, Chad
[2] Univ Dschang, Fac Econ & Management, Ctr Studies & Res Management & Econ CERME, Dschang, Cameroon
[3] Univ Marien Ngouabi Brazzaville, Fac Econ, Brazzaville, Rep Congo