Saavedra, Félix E., et al. “Antimicrobial and Fungicide Activity of Anthraquinones from Aloe Vera L. Combined With Copper, Iron, Silver and Bismuth Cations”. Ciencia E Investigación, vol. 15, no. 1, June 2012, pp. 30-35, https://doi.org/10.15381/ci.v15i1.3190.