1. J.M. Gray and W.J. Fazakerley: 37th Annual Conf. of Metallurgists, Calgary, AB, Canada, 1998, August 16–19, CIM, Canada, 1998, pp. 1–31.
2. C. Ouchi: Iron Steel Inst. Jpn. Int., 2001, vol. 41 (6), pp. 542–53.
3. M. Nagae, S. Endo, N. Mifune, N. Uchitomi, and O. Hirano: NKK Rev., 1992, vol. 66, pp. 17–24.
4. K. Hulka: Niobium Information, CBMM/NPC, 1997, No. 13/97, pp. 1–42.
5. I. Hrivnak, F. Matsuda, and K. Ikeuchi: Trans. JWRI, 1992, vol. 21, pp. 9–32.