Adam, P., R. Rosnawintang, L. O. Saidi, L. Tondi, and L. O. A. Sani. “The Causal Relationship Between Crude Oil Price, Exchange Rate and Rice Price”. International Journal of Energy Economics and Policy, vol. 8, no. 1, Jan. 2018, pp. 90-94, https://www.econjournals.com/index.php/ijeep/article/view/5774.