MATAJANG, S. W.; MUSLIM, E. . Analysis of Product Quality Improvements to Reduce Coffee Bean Defects with Six Sigma Method . Jurnal Sistem Teknik Industri, [S. l.], v. 24, n. 1, p. 107–123, 2022. DOI: 10.32734/jsti.v24i1.7517. Disponível em: https://idjpcr.usu.ac.id/jsti/article/view/7517. Acesso em: 11 aug. 2025.