Bin-Gadeem, F. H. “Laparoscopic Cholecystectomy for Gallbladder Stone disease:Preoperative Factors Associated With Difficult Operations”. University of Aden Journal of Natural and Applied Sciences, vol. 25, no. 1, Apr. 2021, pp. 179-86, doi:10.47372/uajnas.2021.n1.a15.