Akhtar, Muhammad Salim, et al. “COMPARISON OF LATERAL ANAL SPHINCTEROTOMY WITH 0.2% GTN IN CHRONIC ANAL FISSURE: Lateral Anal Sphincterotomy in Chronic Anal Fissure”. Pakistan Armed Forces Medical Journal, vol. 68, no. 3, Oct. 2018, pp. 491-96, https://pafmj.org/PAFMJ/article/view/285.