1. Mark HF, Bikales NM, Overberger CG, Menges G. Encyclopedia of polymer science. 2 nd ed, Vol. 2. NY: John Wiley and Sons, A Willey Interscience Publishers; 1987. p. 739.
2. Mandel M. Encyclopedia of polymer science and technology. 2 nd ed, Vol. 2. Chichester: Wiley; 1988. p. 739-829.