AL-RABASI, DR. AHMED M.G; ALI, DR. FAISAL ALI MOHAMMAD; ABDEL RAZZAQ, DR. AHMED; ABDO, DR. RIAM MOHAMED. X-bar Chart Based on Six Sigma to Continual Quality Improvement: Implementation on Oil Vapor Pressure Characteristic, at Yemen’s Aden Oil Refinery. مجلة العلوم التربوية و الدراسات الإنسانية, [S. l.], n. 25, p. 671–699, 2022. DOI: 10.55074/hesj.v0i25.549. Disponível em: https://hesj.org/ojs/index.php/hesj/article/view/549. Acesso em: 9 نوفمبر. 2026.