Purba, Helena J., Bonar M. Sinaga, Tanti Novianti, and Reni Kustiari. “The Impact of Changes in External Factors on the World Vegetable Oil Market”. International Journal of Economics and Financial Issues 8, no. 6 (November 19, 2018): 176–186. Accessed April 24, 2024. https://www.econjournals.com/index.php/ijefi/article/view/7069.