Arif, T., M. Adil, and J. S. Sodhi. “Upper Gastrointestinal Endoscopy in Systemic Sclerosis: A Cross Sectional Study”. Journal of Pakistan Association of Dermatologists, vol. 29, no. 4, Oct. 2019, pp. 374-83, https://www.jpad.com.pk/index.php/jpad/article/view/1358.