Vannucchi, Hélio, et al. “ Assessment of Vitamin A, E, C and B2, Carotenoid and Zinc Serum Levels in Elderly Hospital Patients ”. Revista De Saúde Pública, vol. 28, no. 2, Apr. 1994, pp. 121-6, https://doi.org/10.1590/S0034-89101994000200005.