1. M. Palladino, Fonderie, 305 (1971) 317.
2. R. Riccardi and C. Sinistri, La Ricerca Sci., 35 (1965) 1026.
3. G. W. Miller and J. L. Wood, J. Thermal Anal., 2 (1970) 71.
4. A. Radenac, C. Chesnad and M. Rapin, Rev. Int. Haut. Temp. Et. Refractories, 7 (1970) 230.
5. M. Garski, Zeit. Angew. Physik 24 (1968) 206.