Kudrin, A. J., V. F. Labunets, and O. A. Vishnevsky. “Exploration of Passive Hardness of Hardened Simple Steel in Conditions of Abrasive Chafing”. Proceedings of National Aviation University, vol. 17, no. 2, June 2003, pp. 111-4, doi:10.18372/2306-1472.2.11928.