Yisak, H., Ewunetei, A., Kefale, B., Mamuye, M., Teshome, F., Ambaw, B., & Yideg Yitbarek, G. (2021). Effects of Vitamin D on COVID-19 Infection and Prognosis: A Systematic Review. Risk Manag Healthc Policy.

Yisak, Hiwot, Amien Ewunetei, Belayneh Kefale, Melkalem Mamuye, Fentaw Teshome, Birhanie Ambaw, und Getachew Yideg Yitbarek. "Effects of Vitamin D On COVID-19 Infection and Prognosis: A Systematic Review." Risk Manag Healthc Policy 2021.

Yisak, Hiwot, et al. "Effects of Vitamin D On COVID-19 Infection and Prognosis: A Systematic Review." Risk Manag Healthc Policy 2021.