Promwong, U., S. Suthutvoravut, S. Patrachai, and V. Singhakajen. “Factors Associated with Pregnancy among Primigravida Adolescents at King Chulalongkorn Memorial Hospital”. Research Medical Journal, vol. 33, no. 4, Dec. 2010, pp. 236-41, https://he02.tci-thaijo.org/index.php/ramajournal/article/view/152225.