Tavares, Warley Luciano Fonseca, et al. “Scanning Electron Microscopic Energy-Dispersive X-Ray Analysis in Cases of Apical Periodontitis Refractory to Endodontic Treatment: A Case Series Study”. Iranian Endodontic Journal, vol. 14, no. 4, Dec. 2019, pp. 306-12, doi:10.22037/iej.v14i4.26018.