Sirin Losuvarat และ Wanna Charoenchang. (2008) Factors affecting work efficiency : staff at Foster Wheeler Service (Thailand) Limited. Language Institute, Thammasat University,:ม.ป.ท.Sirin Losuvarat และ Wanna Charoenchang. 2008. Factors affecting work efficiency : staff at Foster Wheeler Service (Thailand) Limited. ม.ป.ท.:Language Institute, Thammasat University,;Sirin Losuvarat และ Wanna Charoenchang. Factors affecting work efficiency : staff at Foster Wheeler Service (Thailand) Limited. ม.ป.ท.:Language Institute, Thammasat University, 2008. Print.