Kumar, A., Tandon, S., Nagdeote, S.T., Sharma, K., Shrikhande, A. and Gopal, K. 2017. Serum Vitamin D levels in Chronic Obstructive Pulmonary Disease. International Journal of Medical Research and Review. 5, 2 (Feb. 2017), 128-136. DOI:https://doi.org/10.17511/ijmrr.2017.i02.06.