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3. P. Ludwik:Elemente der Technologischen Mechanik, p. 32, Jullus Springer, Berlin, 1909.
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5. W. B. Morrison and R. L. Miller:Ultrafine-Grain Metals, p. 191, J. J. Barke, N. L. Reed, and V. Weiss, eds. Syracuse University Press, 1970.