Al-Hashimi, Raghad A., et al. “A Comparative Evaluation of Apical Seal Associated With Ultrasonic Retrograde Cavities Filled With Bioactive Material (In Vitro Study)”. Journal of Baghdad College of Dentistry, vol. 28, no. 3, Sept. 2016, pp. 15-21, https://doi.org/10.12816/0031103.