1. W. Pauli, Relativistic field theories of elementary particles, Rev. Mod. Phys. 13 (1941), eq. (91), 203–232.
2. 1. B. S. DeWitt, Dynamical Theory of Groups and Fields, Gordon&Breach, New York, 1965, p. 44
3. 2. F. G. Friedlander, The Wave Equation in a Curved Space-Time, Univ. Press, Cambridge, 1975, 178-181.
4. K. Just and E. Sucipto, Basic versus practical quantum induction, in Group 21, Vol. 2, Doebner, Scherer, and Schulte, eds., World Sci. Singapore, 1997, p. 739.
5. G. Esposito, Dirac Operators and Spectral Geometry, Univ. Press, Cambridge, 1998.