Chinachoti, T., S. Saetia, P. Chaisiri, and T. Tritrakarn. “Incidence and Risk Factors of Hypotension and Bradycardia During Spinal Anesthesia”. Siriraj Medical Journal, vol. 58, no. 3, Mar. 2006, pp. 696-01, https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/245717.