Nuttee Sungsuwan. (2007) The advantages of certified organization on external environmental management system audits. Mahidol University,:ม.ป.ท.Nuttee Sungsuwan. 2007. The advantages of certified organization on external environmental management system audits. ม.ป.ท.:Mahidol University,;Nuttee Sungsuwan. The advantages of certified organization on external environmental management system audits. ม.ป.ท.:Mahidol University, 2007. Print.