Thangteekaraks R, Wongtanasarasin W. Absence of Imaging Signs in Perforated Peptic Ulcer. TJEM [internet]. 2022 Jan. 21 [cited 2026 Sep. 19];3(2):28-36. available from: https://he02.tci-thaijo.org/index.php/TJEM/article/view/254687