Campillo-Cortes, C., H. Flores-Reyes, C. Dávila-Pérez, D. Silva-Herzog, V. Méndez-González, and A. Pozos-Guillén. “Effectiveness of Three Electronic Apex Locators to Determine Root Canal Working Length.”. Journal of Oral Research, Vol. 4, no. 4, June 2015, pp. 249-54, doi:10.17126/joralres.2015.049.