Khoiroh, Mawadatul, Dominikus Atmaka, and Putri Ayuningtyas. 2021. “Effectiveness of Vitamin D-Based Therapy in Reducing Clinical Impact of Covid-19 Patients: A Systematic Review”. Romanian Journal of Diabetes Nutrition and Metabolic Diseases 28 (3), 331-36. https://rjdnmd.org/index.php/RJDNMD/article/view/1031.