Woraluk Narongpun และ Damrong Attaprechakul. (2009) A survey middle-level administrators' leadership styles driving government officials' engagement at the Office of the Permanent Secretary of the Interior (OPSI). Language Institute, Thammasat University,:ม.ป.ท.Woraluk Narongpun และ Damrong Attaprechakul. 2009. A survey middle-level administrators' leadership styles driving government officials' engagement at the Office of the Permanent Secretary of the Interior (OPSI). ม.ป.ท.:Language Institute, Thammasat University,;Woraluk Narongpun และ Damrong Attaprechakul. A survey middle-level administrators' leadership styles driving government officials' engagement at the Office of the Permanent Secretary of the Interior (OPSI). ม.ป.ท.:Language Institute, Thammasat University, 2009. Print.