1. R. G. W. Spickett and S. H. B. Wright, British Patent No. 1070243;Chem. Abstr.,67, 100157 (1967).
2. G. W. Miller and F. L. Rose, British Patent No. 897870;Chem. Abstr.,58, 10211 (1963).
3. G. W. Miller and F. L. Rose, British Patent No. 898408;Chem. Abstr.,57, 11209 (1962).
4. Y. Makisumi, H. Kano, and S. Takahashi, Japanese Patent No. 9499(162),Chem. Abstr.,59, 5178 (1963).
5. Y. Makisumi, H. Kano, and S. Takahashi, Japanese Patent No. 9498(162),Chem. Abstr.,59, 5178 (1963).