1. L. D. Landau and E. M. Lifshitz, The Classical Theory of Fields (Pergamon, Oxford, 1993).
2. C.W. Misner, K. S. Thorne, and J. A. Wheeler, Gravitation (Freeman, New York, 1973).
3. P. Schneider, J. Ehlers, and E. Falco, Gravitational Lenses (Springer-Verlag, Berlin, 1992).
4. Swiss Society for Astrophysics and Astronomy Series: Saas-Fee Advanced Courses;P. Schneider,2006
5. P. V. Bliokh and A. A. Minakov, Gravitational Lenses (Naukova Dumka, Kiev, 1989) [in Russian].