Chawanpaiboon, Saifon, Prasert Sunsaneevittayakul, and Anuwat Sutantawibul. 2004. “The Cost Analysis of Ultrasound Screening for Fetal Anomalies”. Siriraj Medical Journal 56 (2):63-68. https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/245486.