M. . Athar, S. . Moied Ahmed, S. . Ali, K. . Doley, A. . Varshney, and M. M. . Hussain Siddiqi, “Levobupivacaine or ropivacaine: A randomised double blind controlled trial using equipotent doses in spinal anaesthesia”, Colomb. J. Anesthesiol., vol. 44, no. 2, pp. 97–104, Apr. 2016.