1. World Health Organization. Global prevalence of vitamin-A deficiency in population at risk 1999–2005. WHO global database on vitamin A deficiency; 2022.
2. Maternal and child undernutrition: global and regional exposures and health consequences
3. World Health Organization. Micronutrient deficiencies: Vitamin A; 2013.
4. Higdone J, Delage B. “Vitamin A”. Micronutrient Information Center, Linus Pauling institute, Oregon State University, Corvallis, January 2015; 2019.