Panturat, P. “Comparison Between Castor Oil and Sodium Phosphates As the Oral Evacuants for Bowel Preparation before Intravenous Pyelography”. Srinagarind Medical Journal, vol. 23, no. 1, Nov. 2013, pp. 107-12, https://li01.tci-thaijo.org/index.php/SRIMEDJ/article/view/13059.