1. R. H. Miller, in Numerical Experiments on Spiral Structure (CNRS International Colloquium No. 241), 1975, p. 43.
2. M. Miyamoto, Publ. Astron. Soc. Jpn. 27, 431 (1975).
3. A. M. Fridman and V. L. Polyachenko, Physics of Gravitating Systems (Nauka, Moscow, 1976; Springer-Verlag, New York, 1984).
4. K. Rohlfs, Lectures on Density Wave Theory (Springer-Verlag, Berlin, 1977; Mir, Moscow, 1980).
5. A. G. Morozov, Astron. Zh. 58, 34 (1981) [Sov. Astron. 25, 19 (1981)].