1. U. S. Patent 4196282 (1980).
2. C. C. J. Culvenor and Ph. D. D. Phil, Rev. Pure and Appl. Chem., No. 20, 89 (1953);
3. P. Navard and J. M. Haudin, J. Therm. Anal., 22, No. 1, 107?118 (1981).
4. L. K. Golova, O. E. Andreeva, and N. V. Vasil'eva, Summaries of Reports at All-Union Conference ?Theory and Practice in Spinning Man-made Fibres?, [in Russian], Mytishchi (1983), p. 10.