1. Kaiser Aluminum & Chemical Corporation, Annual Report (1953–1954), p. 14.
2. R.A. Lewis, U.S. patent 3,034,972 (1962).
3. C.E Ransley, Extractive Metallurgy of Aluminum Volume 2, Aluminum, ed. G. Gerard (New York: Wiley Interscience, 1963), p. 487.
4. J.C. Withers and G.V. Upperman, U.S. patent 4,342,637 (1982).
5. J.C. Withers and G.V. Upperman, U.S. patent 4,338,177 (1982).