1. K. E. Hofer Jr andE. M. Olsen, Technical Report AD 652.415, April 1967.
2. R. F. Boyer,Polymer Eng. and Sci. 8 (1968) 161.
3. J. Heijboer,J. Polymer Sci. 5 (1967) 3755.
4. S. G. Turley,Polymer Preprints, American Chemical Society8 (1968) 1524.
5. E. H. Andrews, ?Fracture in Polymers? (American Elsevier Publishing Company, New York, 1968).