Winarto, W., and C. U. Wirawati. “Response Surface Method Approach for Optimizing Roasting Condition in Robusta Coffee Cupping Test Quality”. Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering), vol. 12, no. 3, Sept. 2023, pp. 610-8, doi:10.23960/jtep-l.v12i3.610-618.