Hossain, Enamul, Sanjay K Mandal, Souvik Sarkar, Amrita Jha, and Ranjan Mondal. 2025. “A Study on Serum Vitamin D3 Level in Patients With Covid-19: A Cross-Sectional Study in Kolkata”. National Journal of Medical Research 15 (02):126-31. https://doi.org/10.55489/njmr.150220251070.