1. Encyclopedia of Chemical Technology;Kirk-Othmer,1993
2. Datta, R, in, Encyclopedia of Chemical Technology, Vol, 13, 4th ed, Wiley, New York, 1995.
3. Johnson, Matthey and Co, Ltd, GB 1208101, 1970.
4. Kawaken Fine Chemicals Co. Ltd, JP 8007230, 1980.
5. Mitsui Toatsu Chemicals Inc, JP 7652121, 1976.