1. Aharonov, Y., and Susskind, L. (1967).Physical Review,158, 1237.
2. Blaine Lawson, Jr., H., and Michelsohn, M. L. (1983).Spin-Geometry, Universidad Federal do Ceará, Brazil.
3. Bleecker, D. (1971).Gauge Theory and Variational Principles, Addison-Wesley, Reading, Massachusetts.
4. Edmonds, J. D. (1975).Letters al Nuovo Cimento,13, 185.
5. Faria-Rosa, M. A., and Rodrigues, Jr., W. A. (1989).Modern Physics Letters A,4, 175.