Mahmood, Haider, and Tarek Tawfik Yousef Alkhateeb. “Trade and Environment Nexus in Saudi Arabia: An Environmental Kuznets Curve Hypothesis”. International Journal of Energy Economics and Policy, vol. 7, no. 5, Nov. 2017, pp. 291-5, https://econjournals.com./index.php/ijeep/article/view/5333.