1. Cottrell, A. H.: Proc. Roy. Soc. (Lond.) A 282, 2 (1964)
2. Andrews, E. H.: Fracture in polymers. London: Oliver & Boyd Ltd. 1968, p. 113
3. Griffith, A. A.: Phil. Trans. Roy. Soc. (Lond.) A 221, 163 (1921)
4. Andrews, E. H.: J. Materials Sci. 9, 887 (1974)
5. Orowan, E.: Proc. Symposium on Fatigue and Fracture of Metals New York: John Wiley & Sons Inc. 1950, p. 139