1. 1) S. Yanagisawa and T. Sirai: Bunseki Kagaku, 15 (1966), 1161.
2. 2) The standard analytical methods of gases in metals, ed. by Japan Titanium Society, Maruzen, (1974), p. 49.
3. 3) T. Shigematsu: Oyo Butsuri, 55 (1986), 1138.
4. 4) T. Koizumi and F. Tsugane: Tetsu-to-Hagané, 50 (1964), 787, 925.
5. 5) K. Furuya and H. Kamata: Bunseki Kagaku, 14 (1965), 708.