1. 1) Covered by U. S. Patents 3 343 930, 3 393 089 and others issued or pending in the U. S. and corresponding Japanese Patent 17,971, 6and others issued or pending in Japan.
2. 2) A. A. PRESNYAKOV, Yu. A. GORBAN, and V. V. CHERVYAKOVA : Zhur. Fiz. Khim., 35 (1961) 6, p. 1289
3. 3) G. R. GOLDAK and J. G. PARR : J. Inst. Metals, 92 (1964) p. 230
4. 4) From an article by H. E. TOWNSEND and J. C. ZOCCOLA of Bethlehem Steel Corporation that has been accepted for publication by Materials Performance, journal of the National Association of Corrosion Engineers
5. 5) U. R. EVANS : "Metallic Corrosion, Passivity and Protection, " 2 nd ed. (1946), p. 536 [Edward Arnold and Son, London]