1. G. Gee,Contemp. Phys. 11 (1970) 313.
2. S. E. B. Petrie, in ?Polymeric Materials: Relationships Between Structure and Mechanical Behavior? (American Society for Metals, Metals Park, Ohio, 1975) pp. 55?118.
3. A. J. Kovacs, J. M. Hutchinson andJ. J. Aklonis, in ?The Structure of Non-Crystalline Materials?, edited by P. H. Gaskell (Taylor and Francis, London, 1977) p. 153.
4. L. C. E. Struik, ?Physical Aging in Amorphous Polymers and Other Materials? (Elsevier, New York, 1978).
5. M. R. Tant andG. L. Wilkes,Polym. Eng. Sci. 21 (1981) 874.