1. ASTM Standard E399-74, Annual Book of ASTM Standards, Part 10 (1976) 432.
2. ASTM Standard E813-81, Annual Book of ASTM Standards (1982) 822.
3. British Standard Institution BS5762, BSI London (1979).
4. G. Irwin, Journal of Basic Engineering, ASME 82 (1960) 417.
5. W. Andrews, W. Kumar and M. Little, ASTM STP 743 (1981) 576.