1. Cartan, H. (1971).Differential Calculus. Hermann, Paris.
2. Dunford, N., and Schwartz, J. T. (1957).Linear Operators Part I. Interscience, New York.
3. Fonte, G. (1979).Nuovo Cimento,49B, 200–219.
4. Hirschfelder, J. O., Brown, W. B., and Epstein, S. T. (1964).Advances in Quantum Chemistry,1, 255–374.
5. Luenberger, D. G. (1969).Optimization by Vector Space Methods. John Wiley, New York.