Chaopotong, Pattama, Suwanit Therasakvichya, Chairat Leelapatanadit, and Boonlert Wiriyapak. 2008. “Incidence, Survival Rate and Prognostic Factors of Recurrent/ Refractory Epithelial”. Siriraj Medical Journal 60 (6):339-43. https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/246507.