1. D. Tabor,Rev. Phys. Tech. 1 (1970) 145.
2. J. H. Westbrook andH. Conrad, Eds., ?The Science of Hardness Testing and its Research Applications?, Symposium Proceedings (American Society for Metals, Metals Park, Ohio, 1973).
3. H. Hertz,J. Reine Angew. Math. 92 (1881) 156;Verhandlungen des Vereins zur Beförderung des Gewerbe Fleisses 61 (1882) 449. Reprinted, in English, in ?Hertz's Miscellaneous Papers? (Macmillan, London, 1896) Chs. 5, 6.
4. A. A. Griffith,Phil. Trans. Roy. Soc. Lond. A221 (1920) 163.
5. D. Tabor, ?The Hardness of Metals? (Clarendon, Oxford, 1951).