Feng, Yan, et al. “RETRACTED: Intravenous Versus Perineural Dexmedetomidine in Prolongation of Analgesia With Regional Anesthesia: A Meta-Analysis and Systematic Review”. Pain Medicine, vol. 6, no. 2, Aug. 2021, pp. 10-28, https://painmedicine.org.ua/index.php/pnmdcn/article/view/255.