Sankhla, A., P. K. Dashora, and A. K. Sankhla. “Vitamin A Status of Urban and Rural Adults of Agra District”. The Indian Journal of Nutrition and Dietetics, vol. 28, no. 8, Aug. 1991, pp. 224-7, https://informaticsjournals.co.in/index.php/ijnd/article/view/8238.