Karadag, M. A.; Demir, A.; Cecen, K.; Bagcioglu, M.; Kocaaslan, R.; Altunrende, F. Flexible Ureterorenoscopy Versus Semirigid Ureteroscopy for the Treatment of Proximal Ureteral Stones: A Retrospective Comparative Analysis of 124 Patients. Urol J 2014, 11, 1867-1872.