Charoenchainont, P., Virojchaiwong, P. and Sakulpaisal, C. (2011) “Transvaginal Sonographic Measuremant of cervical Length in Early Third Trimester as a Predictor of Preterm Delivery”, Vajira Medical Journal : Journal of Urban Medicine, 46(3), pp. 195–203. available at: https://he02.tci-thaijo.org/index.php/VMED/article/view/189 (accessed: 20 September 2026).