Kanchanabat, B., Y. Wongmahisorn, W. Stapanavatr, P. Kanchanasuthiruk, and A. Manomaiphiboon. “Pattern and Prevalence of Venous Reflux in Patients with Lower Extremity Chronic Venous Insufficiency”. Vajira Medical Journal : Journal of Urban Medicine, vol. 52, no. 2, Sept. 2011, pp. 119-28, https://he02.tci-thaijo.org/index.php/VMED/article/view/339.