Prasad, Rakshith B., et al. “Effectiveness of Addition of Intrathecal Tramadol With Hyperbaric Bupivacaine in Prevention of Shivering in Parturients Undergoing Cesarean Section Under Spinal Anesthesia: A Randomized Placebo‑controlled Study”. Karnataka Anaesthesia Journal, vol. 1, no. 3, July 2015, pp. 123-7, https://karnatakaanesthesiajournal.in/index.php/kaj/article/view/139394.