SINGEL, Akash; KRUZ, Walter. Can Six Sigma Effective in Service Sector?. Account and Financial Management Journal, [S. l.], v. 2, n. 11, p. 1167–1171, 2017. Disponível em: http://everant.org/index.php/afmjh/article/view/201. Acesso em: 7 may. 2024.