Ronnapop Kittiakrastien และ Napassavong Osothsilp. (2007) Failure cost reduction in Dioctyl Phthalate manufacturing process using Six Sigma approach. Chulalongkorn University:ม.ป.ท.Ronnapop Kittiakrastien และ Napassavong Osothsilp. 2007. Failure cost reduction in Dioctyl Phthalate manufacturing process using Six Sigma approach. ม.ป.ท.:Chulalongkorn University;Ronnapop Kittiakrastien และ Napassavong Osothsilp. Failure cost reduction in Dioctyl Phthalate manufacturing process using Six Sigma approach. ม.ป.ท.:Chulalongkorn University, 2007. Print.