1. Europe Patent No. 95206, 1983, Chem. Abstr.,100, 102820t (1984).
2. Europe Patent No. 135411, 1985, ibid.,103, 87639g (1985).
3. Europe Patent No. 143017, 1986, ibid., 123064b.
4. Europe Patent No. 159240, 1986, ibid.,104, 129540w, (19860.
5. Europe Patent No. 254228, 1988, ibid.,109, 8398a (1988).