1. O. Winkler and R. Bakish:Vacuum Metallurgy, pp. 212–21, Elsevier, New York, 1971.
2. R. F. Bunshah:Trans. Vacuum. Met. Conf., New York, 1963, p. 121, American Vacuum Society, Mass. 1964.
3. L. Muller:Freiberger Forsch., B33, 1958, quoted by R. F. Bunshah, (in Ref. 2).
4. T. R. A. Davey: Vacuum, 1962, vol. 12, p. 83.
5. B. Ilschener and J. Humbert:Z. Metallic., 1960, vol. 51, pp. 626–31.