1. General Bearing Corporation. http://www.generalbearing.com/JGBR/specs.htm . West Nyack, New York
2. New England Miniature Ball Corporation (NEMB). http://www.nemb.com
3. W. Park, M.R. Hilton, and A.R. Leveille, Microstructure, Fatigue Life and Load Capacity of PM Tool Steel Rex20 for Bearing Applications, Lubric. Eng., 1999, 55(6), p 20–30
4. O’Brien M.J., Pressure M., Robinson E.Y. (2003) Failure analysis of three Si3N4 balls used in hybrid bearings. Eng. Failure Anal. 10:453–473
5. Eastern Tool Steel Services Inc. http://www.easterntoolsteel.com/hea_treatment_of_toolsteels.htm. St. Marys, Pennsylvania