Saputra, Rudi, Andrianto Indra Pratomo, and Sumiyanto Sumiyanto. “Productivity Measurement of Urea Fertilizer Production at PT. X Using The Green Productivity Approach”. Greenation International Journal of Engineering Science 3, no. 4 (January 4, 2026): 183–192. Accessed January 20, 2026. https://research.e-greenation.org/GIJES/article/view/691.