1. Bergström, J.G.T: 1986, Waste management & Research 4, 57.
2. Brosset, C.: 1987, Water, Air and Soil pollut. 35, 145.
3. Dumary, R., Heindryckx, R. and Dams, R.: 1981, Environmental Sc. & Techn. 15, 206.
4. EPON: 1988, EPON/NOVEM report concerning measuring program flue-gas desulphurization.
5. Gloskuter, H.J., Ruch, R.R., Miller, W .G., Cahill, R.A., Dreher, G.B. and Kuhn, J.K.: 1977, Illinois State Geological Survey Circular 499.