1. Ames, J. S. and Murnaghan, F. D., Theoretical Mechanics, Dover, New York, 1958, pp.76-91.
2. Frazer, R. A., Duncan, W. J. and Collar, A. R., Elementary Matrices, University Press, Cambridge, Mass. 1957, pp.246-256.
3. Gibbs, J. W., Vector Analysis, 2nd ed.Yale University Press, New Haven, Conn.1958, pp.332-371.