1. Encyclopedia of Chemical Technology;Kirk-Othmer,1969
2. Preparation of Catalysts, ‘Scientific Bases for the Preparation of Heterogeneous Catalysis’;Hermans,1979
3. A.Q.M. Boon, Ph. D. Thesis, University of Utrecht 1990, The Netherlands, chapter 2.
4. N. Brahma, Ph. D. Thesis, University of Utrecht 1990, The Netherlands, chapter 4.