Mamta Padhy, Hariom Kumar Solanki, Ravoori Saideswar Rao, Ajay Kumar Garg, Manisha Singh, and Vivek Gupta. “A Cross-Sectional Study to Explore the Correlation of Serum Vitamin D3 With Laboratory Parameters Among COVID-19 Patients of a Tertiary Care Centre of Uttar Pradesh, India”. International Journal of Health and Clinical Research, vol. 4, no. 22, Dec. 2021, pp. 181-7, https://ijhcr.com/index.php/ijhcr/article/view/3547.