1. C. S. Stokes, J. A. Cahill, J. J. Correa andA. V. Grosse, Final Report, Grant 62-196, A.F. Office of Scientific Research (1965).
2. E. Neuenschwandter,J. Less Common Metal 11 (1966) 365.
3. J. Sautereau andA. Mocellin,J. Mater. Sci. 9 (1974) 761.
4. J. Canteloup andA. Mocellin, “Special Ceramics 6” edited by P. Popper (B.C.R.A., Stokeon-Trent, 1975) p. 209.