Pergel, A., A. Fikret Yucel, A. Serdar Karaca, I. Aydin, and D. Ali Sahin. “A Rare Cause of Ileus: Gallstone Ileus”. Annals of Medical Research, vol. 17, no. 4, May 2021, pp. 0395-7, http://annalsmedres.org/index.php/aomr/article/view/3498.