1. A.M. Gunn, D.A. Winnard, D.T.E. Hunt, in: Metal Speciation: Theory, Analysis and Application, R.J. Kramer, H.E. Allen (Eds.), Lewis Pub. Inc., Chelsea, 1988, p. 261
2. A. Tessier, P.G.C. Campbell, in: Metal Speciation: Theory, Analysis and Application, R.J. Kramer, H.E. Allen, (Eds.), Lewis Pub. Inc., Chelsea, 1988, p. 183
3. A.M. Ure, in: Heavy Metals in Soils, B.J. Salloway, (Eds.), Blackie and Son, Glasgow 1990, p. 71, Chap. 4
4. Speciation of Heavy Metals in Soils and Sediments. An Account of the Improvement and Harmonization of Extraction Techniques Undertaken Under the Auspices of the BCR of the Commission of the European Communities