Veena, A., A. Amit, S. J. P, and G. V. “Comparison of Intrathecal Sufentanil and Morphine in Addition to Bupivacaine for Caesarean Section under Spinal Anesthesia”. Anaesthesia, Pain & Intensive Care, Feb. 2019, pp. 99-01, https://apicareonline.com/index.php/APIC/article/view/536.