Singh, P., Agrawal, S.K., Dwivedi, S. and Yadav, A. 2017. A comparative evaluation between median and paramedian approaches for sub-arachnoid block in elderly patients. International Journal of Research in Medical Sciences. 4, 6 (Jan. 2017), 2069–2072. DOI:https://doi.org/10.18203/2320-6012.ijrms20161762.