Sirirattanapan, J., S. Chantapan, and S. Pongsawat. “A Rare Upper Airway Obstruction by Large Hemorrhagic Vocal Polyps”. Journal of Medicine and Health Sciences, vol. 22, no. 1, June 2015, pp. 93-98, https://he01.tci-thaijo.org/index.php/jmhs/article/view/58643.