AL-RABASI, D.A.M. (2022) "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, (25), ص 671–699. doi:10.55074/hesj.v0i25.549.