UTOMO, Utomo. A Systematic Literature Review of Six Sigma Implementation in Services Industries. IJIEM - Indonesian Journal of Industrial Engineering and Management, Jakarta, Indonesia, v. 1, n. 1, p. 45–57, 2020. DOI: 10.22441/ijiem.v1i1.8846. Disponível em: https://training-ojs3-publikasi.mercubuana.ac.id/index.php/ijiem/article/view/8846. Acesso em: 28 may. 2026.