1. Amino Resins, in Encyclopedia of Polymer Science and Technology, and Eds. Interscience, New York, 1965, Vol. 2, p. 1.
2. U.S. Patent 3,944,526 (1976).
3. U.S. Patent 3,308,101 (1967).
4. U.S. Patent 4,139,512 (1979);
5. U.S. Patent 4,163,099 (1979).