D. Sjarifudin, H. Kurnia, H. H. Purba, and C. Jaqin, “Implementation of six sigma approach for increasing quality formal men’s jackets in the garment industry”, j. sist. manaj. ind., vol. 6, no. 1, pp. 33–44, Jun. 2022, doi: 10.30656/jsmi.v6i1.4359.