Pho-Ngam, S., and S. Suthutvoravut. “Factors Associated With Pregnancy Among Adolescents in Amphur Phiboon Mangsaharn, Ubon Ratchathani Province”. Ramathibodi Medical Journal, vol. 38, no. 2, June 2015, pp. 135-41, https://he02.tci-thaijo.org/index.php/ramajournal/article/view/95914.