1. C.A. Hodge, N.N. Popovici, Pollution Control in Fertilizer Production, Marcel Dekker Inc., New York, 1994.
2. Descriptive Analysis of the Technical and Economic Aspects of Measures to Reduce Water Pollution Caused by Discharges from the Fertilizer Industry and Other Entailing Nutrient Discharges, Research Report of European Commission (Contract No. B6612-411-89), Brussels, October 1991.
3. N.A. Booker, PhD Thesis, Imperial College of Science and Technology, London (1989).
4. N.A. Booker, M. Streat, in: M. Streat (Ed.), Proceedings of Ion Exchange for Industry, Imperial College, London, 1988, p. 632.
5. Removal of Metal Pollutants (Cd(II) and Cr(III)) from Phosphoric Acid Solutions by Chelating Resins Containing Phosphonic or Diphosphonic Groups