1. J. D. Kendall and H. D. Edwards, British Patent 597,446 (1948);
2. Chem. Abstr., 42, 4604a (1948).
3. H. D. Edwards and J. D. Kendall, British Patent 620,800 (1949);
4. Chem. Abstr., 43, 6650d (1949).
5. H. D. Edwards and J. D. Kendall, U. S. Patent 2,533,233 (1950);