Viporn Katekao. 2001. Distance learning : a case study of Ramkhamhaeng and Sukhothai Thammathirat Open Universities. School of Public Administration, National Institute of Development Administration;
Viporn Katekao. (2001) Distance learning : a case study of Ramkhamhaeng and Sukhothai Thammathirat Open Universities . National Institute of Development Administration/Bangkok.
Viporn Katekao. Distance learning : a case study of Ramkhamhaeng and Sukhothai Thammathirat Open Universities. . Bangkok:National Institute of Development Administration, 2001.
Viporn Katekao. (2001) Distance learning : a case study of Ramkhamhaeng and Sukhothai Thammathirat Open Universities . National Institute of Development Administration/Bangkok.