อิวาง ว., and แก้วคง ก. “Concepts about Basic Astronomy of Students in Elementary Level: A Case Study of a Hmong Ethnic Group”. Journal of Education Studies, vol. 47, no. 3, Sept. 2019, pp. 384-03, https://so02.tci-thaijo.org/index.php/EDUCU/article/view/218891.