1. C. Zweben: J. Met., 1992, July, pp. 15–23.
2. J.B. Oenning and I.S.R. Clark: U.S. Patent 4,988,386, Jan. 29, 1991.
3. P.H. Dawson: GE Co. Rev., 1986, vol. 2 (3), pp. 168–70.
4. R.M. German, K.F. Hens, and L.J. Johson: Int. J. Powder Metall., 1994, vol. 30 (2), pp. 205–15.
5. M.R. Ehlert and E.R. Helderman: U.S. Patent 4,788,627, Nov. 29, 1988.