1. Alexandrov, A. D. (1950).Uspekhi Mathematicheskikh Nauk,5(3, 37), 187 [in Russian].
2. Alexandrov, A. D., and Ovchinnikova, V. V. (1953).Leningrad University Vestnik,11, 94?110 [in Russian].
3. Benz, W. (1977).Journal of Geometry,10, 45?56.
4. Brumberg, V. A. (1991).Essential Relativistic Celestial Mechanics, Adam Hilger, Bristol, England.
5. Cannon, W. H., Lisewski, D., Finkelstein, A. M., and Kreinovich, V. (1986). Relativistic effects in Earth based and cosmic long baseline interferometry, inProceedings of the IAU Symposium 114 ?Relativity in Celestial Mechanics and Astrometry,? Reidel, Dordrecht, pp. 255?256.