Güzide Doğan, et al. “Measurement of Rectal Diameter and Anterior Wall Thickness by Ultrasonography in Children With Chronic Constipation”. Turkish Journal of Gastroenterology, vol. 33, no. 12, Dec. 2022, pp. 1062-8, https://tjg.avesjournals.com/index.php/tjg/article/view/4370.