Ma’arif, Moch. Syamsul, et al. “The Influence of Eugenol in Lubrication Properties of Crude Jatropha Curcas Lin”. International Journal of Integrated Engineering, vol. 16, no. 2, May 2024, pp. 164-7, https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/16167.