Sasiwimol Tongpua และ Areewan Cheawchanwattana. (2013) Factors associated with parents' decision on purchasing optional vaccines: An interview study at Health Promotion Center 6, Khon Kaen. <i>Isan Journal ofPharmaceutical Sciences</i>, <i>9</i>(2), 37-49.Sasiwimol Tongpua และ Areewan Cheawchanwattana. "Factors associated with parents' decision on purchasing optional vaccines: An interview study at Health Promotion Center 6, Khon Kaen". Isan Journal ofPharmaceutical Sciences 9 (2013):37-49.Sasiwimol Tongpua และ Areewan Cheawchanwattana. Factors associated with parents' decision on purchasing optional vaccines: An interview study at Health Promotion Center 6, Khon Kaen. Faculty of Pharmaceutical Sciences KKU MSU UBU:ม.ป.ท. 2013.