Udayashankar, C., C. Sathyamoorthy, D. Bhuvaneswari, and A. K. Nath. “Purpura and Bleeding Due to Calcium Channel Blockers: A Preliminary Study”. Journal of Pakistan Association of Dermatologists, vol. 26, no. 4, Apr. 2017, pp. 322-7, https://www.jpad.com.pk/index.php/jpad/article/view/981.