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2. 2) Y. Wanibe and K. Sano: Trans. JIM, 9 (1968), 19.
3. 3) Japan Society of the Promotion of Science, 19th Committee: The Complete Book of Chemical Analysis of Iron and Steel, 8, Daily Newspaper of Engineering, (1963).
4. 4) S. Maekawa and S. Ebihara: Japan Society of the Promotion of Science, 19th Committee, Report No. 4168 (1956);
5. S. Maekawa and S. Ebihara: Analytical Chemistry, 6 (1957), 715.