Sarita Gupta, Vikram K. Mahajan, Rajinder S. Yadav,  Karaninder S. Mehta , Satya Bhushan,Pushpinder S. Chauhan,  Ritu Rawat , and  Vikas Sharma . Evaluation of Serum Vitamin D Levels in Patients with Systemic Sclerosis and Healthy Controls: Results of a Pilot Study.Indian Dermatol Online J. 2018 Jul-Aug; 9(4): 250–255