M. A. Karadag, A. Demir, K. Cecen, M. Bagcioglu, R. Kocaaslan, and F. Altunrende, “Flexible Ureterorenoscopy versus Semirigid Ureteroscopy for the Treatment of Proximal Ureteral Stones: A Retrospective Comparative Analysis of 124 Patients”, Urol J, vol. 11, no. 05, pp. 1867–1872, Nov. 2014.