1. B. Mason , Principles of Geochemistry, Wiley, New York, 3rd edn., 1958, p. 137.
2. K. H. Wedephol , Geochemistry, Holt, Rinehart and Winston, New York, 1971, p. 185.
3. E. B. Sandell , Colorimetric Determination of Traces of Metals, Interscience, New York, 3rd edn., 1959, pp. 868–882.
4. K. Burger , Organic Reagents in Metal Analysis, Pergamon Press, Oxford, 1973, p. 200.
5. Flow injection analyses