1. A.E. Bravo, H.A. Durán, V.H. Jacobo, A. Ortiz, R. Schouwenaars: Wear, 2013, vol. 302, 1–2, pp. 1528-35.
2. E. Rabinowicz: ASLE Trans 14:3, 1971, pp. 198-205.
3. K. Sakai, K. Zushi, M. Sugita, and H. Ishikawa: SAE Technical Paper, 2004-01-1600, 2004.
4. K. Hiromitsu, K. Kazuma, A. Seigi, and H. Hiroyoshi: U.S. Patent, US 2006 0157167 A1, 2006.
5. J. Saleh: U.S. Patent, US 2004 0238086 Al, 2004.