1. Mitsui Toatsu Chemicals, Inc., Japanese Patent Number 83455 (1981).
2. Ajinomoto, Japanese Patent Number 4156 (1985).
3. Mitsui Toatsu Chemicals Inc., Japanese Patent Number 7746313 (1977).
4. Fuji Photo Film Co. Ltd., Japanese Number 189466 (1987).
5. Fuji Photo Film Co. Ltd., Japanese Patent Number 41850 (1988).