Efficacy and safety of ultrasound-guided above-knee lateral approach for popliteal sciatic nerve block in surgeries below the knee: a randomized controlled trial - Zhu, Lin-Jia; Gong, Chan-Juan; Zhang, Zhen-Feng; Zhang, Qing-Wei; Peng, Pei-Pei; Ni, Yan (Annals of Palliative Medicine, 2021)