1. ASTM E813-88, Standard Test Method for JIc, A Measure of Fracture Toughness (1988) 698?712.
2. BS 5762: Crack Opening Displacement (COD) Testing, British Standard Institute, London (1979) 1?12.
3. D. Broek, Engineering Fracture Mechanics 6 (1974) 173?188.
4. W.D. Cao and X.P. Lu, International Journal of Fracture 25 (1984) 33?52.
5. V.R. Ranganath, Ph.D. thesis, Indian Institute of Technology, Delhi (1987).