Chawanpaiboon, S., A. Sutantawibul, S. Kanokpongsakdi, and C. Kangkagate. “Reference Centile Chart for Umbilical Vein Maximum Flow Velocity in Thai Fetuses Throughout Pregnancy”. Siriraj Medical Journal, vol. 59, no. 6, Nov. 2007, pp. 278-80, https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/246157.