Musa, M., A. M. Abdullah, M. M. Ismail, M. Y. Saari, and I. Abdurofi. “Labour Efficiency In The Malaysian Oil Palm Plantations”. Journal of Agribusiness Management and Development, Vol. 2, no. 1, July 2021, pp. 1-10, https://journal.ugm.ac.id/v3/JAMADEV/article/view/2260.