1. L. D. Landau and E. M. Lifshitz,The Classical Theory of Fields, 2nd ed. (Pergamon Press, London, 1962), p. 6.
2. W. Pauli,Theory of Relativity (Pergamon Press, New York, 1958.
3. R. Courant and D. Hilbert,Methods of Mathematical Physics (Interscience, New York, 1962), Vol. II.
4. H. Weyl,Space-Time-Matter (Dover, New York, 1952).
5. J. L. Anderson,Principles of Relativity Physics (Academic, New York, 1967).