Poomlek, Voraporn, Wanut Chaitree, Punnarerk Thongcharoen, Pradit Panchavinnin, and Nisarat Opartkiattikul. 2008. “A Comparative Study of Portable Monitors (CoaguCheck®XS) for International Normalized Ratio (INR)”. Siriraj Medical Journal 60 (1):10-13. https://he02.tci-thaijo.org/index.php/sirirajmedj/article/view/246293.