Chaopotong, P., S. Therasakvichya, C. Leelapatanadit, and B. Wiriyapak. “Incidence, Survival Rate and Prognostic Factors of Recurrent/ Refractory Epithelial”. Siriraj Medical Journal, vol. 60, no. 6, Nov. 2008, pp. 339-43, https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/246507.