1. Bilby, B. A. and Eshelby, J. D., Fracture (ed. H. Liebowitz) Vol. 1, p. 99. Academic Press, New York 1968
2. Zener, C., Fracturing of metals. Cleveland Symposium, A.S.M. 1948
3. Friedel, J., Dislocations. Pergamon, Oxford 1964
4. Guidera, J. T. and Lardner, R. W., Penny-shaped cracks. To be published
5. Lardner, R. W. and Tupholme, G. E., Dislocation layers applied to moving crack problems. Int. J. Frac. Mechs. To appear