Chhetri, N., A. Chhetri, G. C. Bhattacharya, A. Mukherjee, S. Sen, and A. Kumar. “Vitamin D Status in Outpatient Department Patients: A Retrospective Study”. International Journal of Research in Medical Sciences, vol. 4, no. 6, Jan. 2017, pp. 2276-80, doi:10.18203/2320-6012.ijrms20161799.