1. N. E. Erost, K. J. Marsh, and L. P. Pook, Metal Fatigue, Clarendon Press, Oxford (1974).
2. L. P. Pook and A. F. Greenan, in Fracture Mechanics, STP 677, American Society for Testing and Materials, Philadelphia (1979) 22?35.
3. I. C. Howard, International Journal of Fracture 14 (1978) R307-R310.
4. L. P. Pook, Mode I Branch Cracks and Their Implications for Combined Mode Failure, NEL Report (in preparation).
5. D. P. Rooke and D. J. Cartwright, Compendium of Stress Intensity Factors, HMSO London (1976).