1. J.H. Weber, in: R.F. Christman, E.T. Gjessing (Eds.), Aquatic and Terrestrial Humic Materials, Ann Arbor Science, Ann Arbor, 1983, p. 315.
2. Stability constants of copper-organic chelates in aquatic samples
3. G.R. Aiken, D.M. McKnight, R.L. Wershaw, P. MacCarthy (Eds.), Humic Substances in Soil, Sediment, and Water: Geochemistry Isolation and Characterization, Wiley, New York, 1985, p. 691.
4. Fulvic acid studies: evidence for a polycarboxylate co-ordination mode at soil pH
5. Composition and Stability of Iron and Copper Citrate Complexes in Aqueous Solution