Syahril, Syahril, et al. “The Effect of Global Prices of Crude Palm Oil, Marketing Margins and Palm Oil Plantations on the Environmental Destruction: An Application of Johansen Cointegration Approach”. International Journal of Energy Economics and Policy, vol. 9, no. 4, June 2019, pp. 305-12, https://econjournals.com/index.php/ijeep/article/view/8010.