Souwapa kuanun และ Saravudh Sutummasa. (2013) Self evaluation of the cost-benefit on the investment in occupational safety and health. Mahidol University:ม.ป.ท.Souwapa kuanun และ Saravudh Sutummasa. 2013. Self evaluation of the cost-benefit on the investment in occupational safety and health. ม.ป.ท.:Mahidol University;Souwapa kuanun และ Saravudh Sutummasa. Self evaluation of the cost-benefit on the investment in occupational safety and health. ม.ป.ท.:Mahidol University, 2013. Print.