1. B. Wunderlich, Macromolecular Physics Vol. 3. Academic Press, New York 1980, p. 48.
2. P. J. Flory, Principles of Polymer Chemistry, Cornell, Ithaca 1953, p. 569.
3. D. C. Bassett, Principles of Polymer Morphology, Cambridge University Press, Cambridge 1981, p. 69.
4. B. Wunderlich, Macromolecular Physics Vol. 3. Academic Press, New York 1980, p. 40