1) For example, Steel Research Center: Progress Report 2001, (National Institute for Materials Science, Tsukuba, 2002), Preliminary matters, pp. 15-30.
2) Japanese Standard Association: JIS G 4051, (Heat Treatment-2004, Japanese Standard Association, Tokyo, 2004), p. 1084.
3) For example and H. Kuwahara: PhD Thesis, The University of Kyoto (1992).
4) Committee of Nitriding Tool Steels: Data on the hardness at elevated temperature and heat check examination on ion nitrided tool steels, (The Japan Society for Heat Treatment, 1980).