1. O. Buck, J. D. Frandsen, and H. L. Marcus: ASTM STP 595, American Society for Testing and Materials, 1976.
2. O. Buck, J. D. Frandsen, and H. L. Marcus:Eng. Fract. Mech., 1975, vol. 7, pp. 167–71.
3. W. Elber: STP 486, pp. 230. American Society for Testing and Materials, Philadelphia, 1971.
4. M. Katcher and M. Kaplan: STP 559, p. 208, American Society for Testing and Materials, 1974.
5. P. E. Irving, J. L. Robinson, and C. J. Beevers,Int. J. Fract., 1973, vol. 9, pp. 105–08.