1. Saudi Economic Association, Economic Advisor, DSC, Riyadh, Saudi Arabia
2. Department of Economics, University of Perugia, Perugia, Italy and KAPSARC, King Abdullah Petroleum Studies and Research Center, Riyadh, Saudi Arabia
3. University of Perugia, Perugia, Italy
4. KAPSARC, King Abdullah Petroleum Studies and Research Center, Riyadh, Saudi Arabia