References

Four-ball wear.

Investigation of Antiwear Additives for Synthetic Esters.
Ichiro Minami, Toshiaki Hasegawa
Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in San Francisco, CA, USA, October 21-24, 2001
Published in the January 2002 edition of Lubrication engineering.