Kramer, A. S., M. Thomas, A. Makowski, and D. Drozek. “The Prevalence of Vitamin D Deficiency in Impoverished Communities in Northern Lima, Peru”. International Journal of Disease Reversal and Prevention, vol. 3, no. 2, May 2021, p. 10 pp, doi:10.22230/ijdrp.2021v3n2a257.