1. G. F. Khil’mi,Dokl. Akad. Nauk SSSR,70, 393 (1950).
2. Su-Shu Huang,Astron. J.,59, 137 (1954).
3. D. Lynden-Bell,Mon. Not. R. Astron. Soc.,136, 101 (1967).
4. G. N. Duboshin and A. 1. Rybakov,Astron. Zh.,46, 895 (1969).
5. L. P. Osipkov, in:Stellar Clusters and Problems of Stellar Evolution [in Russian], Izd. Ural. Inst., Sverdlovsk (1983), p. 20.