Hung, Nguyen Van, L. Gerbaud, R. Souchal, C. Urbanczyk, and C. Fouchard. 2016. “Penetration Rate Prediction for Percussive Drilling With Rotary in Very Hard Rock”. Vietnam Journal of Science and Technology 54 (1):133-49. https://doi.org/10.15625/0866-708X/54/1/5956.