Handayani, E.S., Setyoningrum, R.A. and Wungu, C.D.K. 2022. Efficacy of vitamin D supplementation on the incidence of recurrent pneumonia in children: A systematic review and meta-analysis study. International journal of health sciences. 6, S4 (May 2022), 2267–2280. DOI:https://doi.org/10.53730/ijhs.v6nS4.7179.