1. P. D. Bayer andR. E. Cooper,J. Matls. Sci. 2 (1967) 233.
2. A. A. Griffith,Trans. Roy. Soc. A 221 (1920) 163.
3. W. C. Dash, ?Growth and Perfection of Crystals?, edited by R. H. Doremus, B. W. Roberts, and D. Turnbull (Wiley, New York, 1958), p. 189.
4. D. M. Marsh, ?Fracture of Solids?, edited by D. C. Drucker and J. J. Gilman (Wiley, New York, 1963), p. 119.
5. F. P. Mallinder andB. A. Proctor,Phil. Mag. 13 (1966) 197.