1. The Synthetic Resins and Their Plastics;Ellis,1923
2. Polymers as Aids in Organic Chemistry;Mathur,1980
3. P. Smit, U.S. Patent 2,191,063 (1940) and French Patent 805,092 (1936).
4. O. Liebknecht, U.S. Patent 2,191,060 (1940) and French Patent 808,612 (1936).