1. Ackerman, B. A., S. R. Ackerman, J. W. Sawyer & D. W. Henderson, 1974. The Uncertain Search for Environmental Quality. The Free Press, New York, 386 pp.
2. Anonymus, 1978. A general plan for the water use in Southern Ostrobothnia (in Finnish). Natl. Bd. Waters, Finland, Rep. 140.
3. Beck M.B., 1983. Uncertainty, system identification, and the prediction of water quality. In: M. B. Beck & G. Van Straten (eds.), Uncertainty and Forecasting of Water Quality. Springer-Verlag, Berlin: 3 - 68.
4. Chiaudani, G. & M. Vighi, 1974. The N:P ratio and tests with Selenastrum to predict eutrophication in lakes. Water Research 8: 1063 - 1069.
5. Flett, R. J., D. W. Schindler, R. D. Hamilton & N. E. R. Campbell, 1980. Nitrogen fixation in Canadian precambrian shield lakes. Can. J. Fish. Aquat. Sci. 37: 488-493.