Putra, G. A., and N. Fajrah. “PENGENDALIAN KUALITAS PRODUK PIPA DI PT.CITRA TUBINDO TBK”. Computer and Science Industrial Engineering (COMASIE), vol. 4, no. 3, Jan. 2021, pp. 126-33, https://forum.upbatam.ac.id/index.php/comasiejournal/article/view/3425.