1. R. M. Spriggs, J. Am. Ceram Soc.
44 (1961) 628.
2. S. Howard, J. Tani, H. Arnold, Schwetlick and W. Sachse, in “NDE of microstructure for process control”, Vol. II edited by H.N.G. Wadley (ASM, Ohio, 1985) p. 81.
3. A. Nagarajan, J. Appl. Phys.
42 (1971) 3693.
4. W. Kreher, J. Ranachowski and F. Rajmund, Ultrasonics
14 (1971) 70.
5. PhD thesis;J. P. Panakkal,1991