1. World Resources Institute, ‘World Resources 1988–89’, Basic Books, New York, 1988, p.372.
2. ‘Inorganic Contaminants of Surface Water’;Moore,1991
3. ‘Water Treatment and Waste Recovery - Advanced Technology and Applications’;Cheremisinoff,1993
4. ‘Foam Flotation: Theory and Applications’;Clarke,1983
5. ‘Ion Flotation’;Sebba,1962