Chanprapaph, Pharuhas, Chanane Wanapirak, and Theera Tongsong. 2017. “Umbilical Artery Doppler Waveform Indices in Normal Pregnancies”. Thai Journal of Obstetrics and Gynaecology 12 (2). Bangkok, Thailand:103-7. https://he02.tci-thaijo.org/index.php/tjog/article/view/97027.