Masood, Quratulain Fatima, et al. “A CASE OF NON-SURGICAL PNEUMOPERITONIUM: GAS UNDER THE DIAPHRAGM”. Journal of Ayub Medical College Abbottabad, vol. 21, no. 2, June 2009, pp. 176-7, https://jamc.ayubmed.edu.pk/index.php/jamc/article/view/3657.