Jirattigalachote, A., and J. Prechapanich. “Emergency cesarean section rate in the women aged 35 or older compared to those aged 21-25 at Siriraj Hospital”. Thai Journal of Obstetrics and Gynaecology, vol. 16, no. 3, Apr. 2017, pp. 155-62, https://he02.tci-thaijo.org/index.php/tjog/article/view/82254.