Diwakaran, R., Parthasarathy, S., & Krishnaveni, N. (2019). Comparative evaluation of addition of either fentanyl or clonidine to bupivacaine in spinal anesthesia – a randomized controlled trial. Anaesthesia, Pain & Intensive Care, 223-227. Retrieved from https://apicareonline.com/index.php/APIC/article/view/133