Arithat Ingkarudphusit และ Sakol Teeravarunyou. (2012) Effect of symbolic representation on children’s imagination play. King Mongkut’s University of Technology Thonburi:ม.ป.ท.Arithat Ingkarudphusit และ Sakol Teeravarunyou. 2012. Effect of symbolic representation on children’s imagination play. ม.ป.ท.:King Mongkut’s University of Technology Thonburi;Arithat Ingkarudphusit และ Sakol Teeravarunyou. Effect of symbolic representation on children’s imagination play. ม.ป.ท.:King Mongkut’s University of Technology Thonburi, 2012. Print.