Jongrak Hong-ngam และผู้แต่งคนอื่นๆ. (2011) The effects of cognitive and non-cognitive skills on earnings : the case of Mueang District, Khonkaen Province of Thailand. National Institute of Development Administration:ม.ป.ท.Jongrak Hong-ngam และผู้แต่งคนอื่นๆ. 2011. The effects of cognitive and non-cognitive skills on earnings : the case of Mueang District, Khonkaen Province of Thailand. ม.ป.ท.:National Institute of Development Administration;Jongrak Hong-ngam และผู้แต่งคนอื่นๆ. The effects of cognitive and non-cognitive skills on earnings : the case of Mueang District, Khonkaen Province of Thailand. ม.ป.ท.:National Institute of Development Administration, 2011. Print.