MOTION ALONG POLAR ORBITS IN THE KERR-NEWMAN SPACETIME Article Cindra J.L. Classical and Quantum Gravity. Vol. 6. 1989. P. 857-865
ON THE GRAVITATIONAL FIELD OF A MASS ENDOWED WITH MAGNETIC DIPOLE MOMENT Article Gutsunaev Ts.I., Elsgolts S.L. Classical and Quantum Gravity. Vol. 4. 1987. P. L211-L213
A CONFORMALLY INVARIANT THEORY OF GRAVITATION AND ELECTROMAGNETISM Article Merkulov S.A. Classical and Quantum Gravity. Vol. 1. 1984. P. 349-354