Comparison of flexible ureteroscopy with flexible and navigable suction ureteral access sheath and mini-percutaneous nephrolithotripsy for the treatment of impacted upper ureteral stones: a retrospective study - Tang, Haiyang; Che, Yulong; Wu, Zhanpeng; Yuan, Fangchao; Liu, Jiayu; Li, Jie (Frontiers in Surgery, 2025)