1. Referent, Encyclopedia of Polymer Science and Technology, Suppl. Vol. 1, p. 120, Interscience, New York 1976.
2. (Assign. to Phillips Petroleum Co.) U.S. Patents 3 485 771 (1969).
3. 3 625 864 and 3 622 522 (1971).
4. 3 646 000 and 3 676 417 (1972).
5. 3 715 321 (1973).