1. Batrakov, Yu.V., Izvekov, V.A., Vashkevich, A.S.: 1987, in Sovremennaya Astrometriya, Pulkovo Observatory, Leningrad, pp. 284–296 (in Russian).
2. Brouwer, D.: 1935, Astron. J.
44, 57–63.
3. Duma, D.P.: 1985, in Problemy Astrometrii, Moscow University, pp. 244–247 (in Russian).
4. Numerov, B.V.: 1935, Astronom. Zh.
12, 339–345 (in Russian).
5. Orelskaya, V.I.: 1981, Pis’ma v Astron. Zh.
6, 654–662 (in Russian).