1. T. A. Agekyan, Vestn. Leningr. Univ., Ser. Mat., Mekh., Astron., No. 1, 152 (1962).
2. L. A. Aguilar and D. Merritt, Astrophys. J. 354, 33 (1990).
3. V. A. Antonov, in Proceedings of the All-Union Workshop on Dynamics of Galaxies and Star Clusters, Alma-Ata, October 23–26, 1972, Ed. by T. B. Omarov (Nauka, Alma-Ata, 1973), p. 139.
4. J. Barnes, J. Goodman, and P. Hut, Astrophys. J. 300, 112 (1986).
5. G. Bertin, F. Pegoraro, F. Rubini, and E. Vesperini, Astrophys. J. 434, 94 (1994).