1. Impact Wear of Materials;Engel,1976
2. Impact Wear, in ASM Metals Handbook: Friction, Lubrication and Wear Technology;Engel;Wear,1992
3. General microhardness indentation theory for multilayer contacts;Engel,1993
4. Microhardness evaluation for multiplated electrical contacts;Engel,1993
5. Hardness, friction and wear in multiplated electrical contacts;Engel;Wear,1993