1. International Standard ISO 12240-1:1998. Spherical plain bearings – Part 1: radial spherical plain bearings.
2. American Standard ANSI/ABMA Std. 22.2-1988. Spherical Plain Radial Bearings, Joint-type – Inch Design.
3. SKF website: 〈http://www.skf.com/mena/products/bearings-units-housings/plain-bearings/general/selection-and-application/selecting-bearing-size/loads/equivalent-static-load/index.html〉.
4. On the contact of elastic solids;Hertz;J Reine Angew Math,1882
5. Contact Mechanics;Johnson,1985