Sachithananthan, V., and U. Chandrasekhar. “Nutritional Status and Prevalence of Vitamin A Deficiency Among Preschool Children in Urban Slums of Chennai City”. The Indian Journal of Nutrition and Dietetics, vol. 42, no. 6, June 2005, pp. 259-65, https://informaticsjournals.com/index.php/ijnd/article/view/6425.