1. Clauser, H. R. Encyclopedia/Handbook: Materials, Parts and Finishes. Technomic Pub., Lancaster, PA USA, 1987, p. 218.
2. Erickson, D., Scientific American, November 1991, 130.
3. Smith, G., APP Report No. 1662, Amoco Polymers, Alpharetta, GA, USA, 1994.
4. ASTM Designation D 638-82a, Annual Book of ASTM Standards, 1984.