Kishnani, P., Jain, L.K., Patel, K. and Chauhan, D. 2022. A study of intrathecal fentanyl and butorphanol as an adjuvant to 0.5% bupivacaine [heavy] for lower limb surgeries: Randomized control study. International journal of health sciences. 6, S3 (Apr. 2022), 1600–1608. DOI:https://doi.org/10.53730/ijhs.v6nS3.5709.