Piya Lasunonth และ Tanompong Panich. (2013) Motivation factors influencing employee performances;a case study of NPC safety and environmental service c ompany. Stamford International University:ม.ป.ท.Piya Lasunonth และ Tanompong Panich. 2013. Motivation factors influencing employee performances;a case study of NPC safety and environmental service c ompany. ม.ป.ท.:Stamford International University;Piya Lasunonth และ Tanompong Panich. Motivation factors influencing employee performances;a case study of NPC safety and environmental service c ompany. ม.ป.ท.:Stamford International University, 2013. Print.