1. Champaigne J, Shot Peen Specif Spring 20 (2006) 12.
2. Leghorn G, A.S.N.E. Journal (1957) 653.
3. Carry P E, in International Conference on Shot Peening 1 (1981) 23.
4. Bush J J, US Patent # 3073022 (1963).
5. Eckstein George R, and Foote Donald S, US Patent # 3204320 A (1965).