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2. P.D. Merica, R.G. Waltenberg, and H. Scott, Sci. Papers of the U.S. Bureau of Standards #347, Vol.15, 271–316 (1919);AIME Bull, 150, 913–949 (1919).
3. H.Y. Hunsicker and H.C. Stumpf, “History of Precipitation Hardening”, Chapter 18 inThe Sorby Centennial Symposium on the History of Metallurgy, C.S. Smith, Ed., Gordon and Breach (1965).
4. A. Wilm,Metallurgie, 8, 225 (1911).
5. F.C. Frary (1915), cited by Z. Jeffries inAge Hardening of Metals, ASM, 5 (1939).