Brownell, N., and C. Kumtornrut. “Cutaneous hyperpigmentation induced by daclatasvir, sofosbuvir, and ribavirin combination therapy”. Thai Journal of Dermatology, vol. 33, no. 2, June 2017, pp. 173-9, https://he02.tci-thaijo.org/index.php/TJD/article/view/159246.