Bussaba Suteetorn และผู้แต่งคนอื่นๆ. (2003) Patterns of dropout in Thai distance education university : Sukhothai Thammatirat Open University. National Institute of Development Administration:ม.ป.ท.Bussaba Suteetorn และผู้แต่งคนอื่นๆ. 2003. Patterns of dropout in Thai distance education university : Sukhothai Thammatirat Open University. ม.ป.ท.:National Institute of Development Administration;Bussaba Suteetorn และผู้แต่งคนอื่นๆ. Patterns of dropout in Thai distance education university : Sukhothai Thammatirat Open University. ม.ป.ท.:National Institute of Development Administration, 2003. Print.