Ali, A., and K. M. Babar. “Comparison of Preoperative Dose of Pregabalin With Celecoxib for Attenuation of Postoperative Pain After Open Cholecystectomy”. Anaesthesia, Pain & Intensive Care, Feb. 2019, pp. 137-41, https://apicareonline.com/index.php/APIC/article/view/507.