Anas, K., Budha Maryanti, and Kuswandi Arifin. “Analysis Comparison Of Spindle Rate Surface Roughness AISI 4140 Using Face Mill: Surface Roughness”. Jurnal Rekayasa Mesin Dan Inovasi Teknologi, vol. 3, no. 2, Sept. 2022, pp. 201-7, https://jurnal.ftm.uniba-bpn.ac.id/index.php/REMIT/article/view/45.