El-Shaib, M., O. Keshk, and M. Shehadeh. “Monitoring of Deep Groove Ball Bearing Defects Using the Acoustic Emission Technology”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 29, no. 2, Aug. 2016, pp. 237-4, https://gssrr.org/index.php/JournalOfBasicAndApplied/article/view/6263.