1. See an early account in English by: A. Wahlberg, J. Iron Steel Inst. 59 (1901) 243.
2. B.W. Mott, Micro-indentation Hardness Testing, Butterworths, London, 1956.
3. D. Tabor, Hardness of Metals, Clarendon Press, Oxford, 1951.
4. M. Bauccio (Ed.), ASM Metals Reference Book, third ed., ASM International, Materials Park, 1993.