1. Abraham, R., and Marsden, J. E. (1978).Foundations of Mechanics, §3.3, Benjamin, Reading, Massachusetts.
2. Belyaev, S. (1965).Nuclear Physics,64, 17.
3. Fock, V. (1930)Zeitschrift für Physik,61, 126.
4. Hartree, D. R. (1927?28).Proceedings of the Cambridge Philosophical Society,24, 89.
5. Kostant, B. (1970). InLecture Notes in Mathematics, Vol. 170, Springer, New York.