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3. L. F. Coffin, Jr.:Trans. Quart. ASM, 1963, vol. 56, p. 339.
4. Report R63FPD124;W. R. Butts,1963
5. H.J. Murphy and C. D. Walker: General Electric Co., Schenectady, N.Y., unpublished work, 1967 and 1968.