الغيلي رياض يحيى حسين, and الأغبري صفوان عبدالوارث , translators. “The Applicability of Sigma Six Pharmaceutical Factories in the Republic of Yemen”. Journal of Social Studies, vol. 21, no. 3, Dec. 2015, pp. 201-42, https://doi.org/10.20428/jss.v21i3.907.