S., L.R., Avala, R., Varma, R., Narahari, N., K., B. and G. K., P. 2018. Prevalence of vitamin D deficiency in chronic obstructive pulmonary disease and it’s correlation with forced expiratory volume in one second: a tertiary care centre study. International Journal of Research in Medical Sciences. 6, 7 (Jun. 2018), 2396–2400. DOI:https://doi.org/10.18203/2320-6012.ijrms20182824.