1. R. L. Samuel and N. A. Lockington:Metal Treat., 1951, vol. 18, p. 354 ; 1952,vol. 19,p.27.
2. I. A. Menzies and 0. Mortimer:Con. Sci, 1965, vol. 5, p. 539.
3. N. V. Karyakina and G. N. Dubinin:Phys. Metals Metallogr., 1960, vol. 9, p. 832.
4. Y. Komem, B. Z. Weiss, and S. Niedzwiedz:J. Iron Steel Inst., 1968, vol. 206, p. 487.
5. J. E. Campbell, V. D. Barth, R. Hockelman, and B. W. Gonser:Trans. Electro- chem. Soc, 1949, vol. 96, p. 262.