1. S. Dunbrant and O. Samuelson, J.Appl.Polymer Sci., 9, 136 (1957).
2. R. Bartunek, Koll.-Z., 146, 35 (1956); Khim.i Tekhnol.Polimerov, No.6 (1967).
3. L.A.Molochnaya and M.E.Shor, Fibre Chemistry, No.2 (1969).
4. G.N.Musatova, D.N.Arkhangelskii, M.A.Ginzberg, and E.M.Mogilevskii, Khim.Volokna, No.4 (1962).