Randomized controlled study f entanyl Vs buprenorphine as adjuvants in subarachnoid block with 2-chloroprocaine in anorectal surgery . AJPHS [Internet]. 2020 Sep. 30 [cited 2026 Feb. 27];10(3):2348-54. Available from: https://www.ajphs.com/index.php/ajphs/article/view/605