1. J. Miklowitz, J. Appl. Mech. 20, 122 (1953).
2. J. W. Phillips, Intern. J. Solids Struct. 6 1403 (1970).
3. Y. Ohno, S. Hyodo, J. Mat. Sci. Soc. Jap 6, 44 (1969).
4. J. J. Gilman, Mech. Engin. 83, No. 9, 55 (1961).
5. See, for example, J. E. Field, Contemp. Phys. 12, No. 1, 1 (1971).