Wang, Z., Joshi, A., Leopold, K., Jackson, S., Christensen, S., Nayfeh, T., Mohammed, K., Creo, A., Tebben, P., & Kumar, S. (2021, June 23). Association of Vitamin D Deficiency with COVID‐19 Infection Severity: Systematic Review and Meta‐analysis. Wiley Online Library. https://onlinelibrary.wiley.com/doi/10.1111/cen.14540?af=R.
Ding, Hong, Deng, Wenjun, Ding, Lingling, Ye, Xiaoqun, Yin, Shanye, & Huang, Weishan. (2020). Glycyrrhetinic acid and its derivatives as potential alternative medicine to relieve symptoms in nonhospitalized COVID‐19 patients. Journal of Medical Virology, 92(10), 2200–2204. https://doi.org/10.1002/jmv.26064