1. Lifshitz, E. M. (1946).Zh. Eksp. Teor. Fiz.,16, 587.
2. Lifshitz, E. M., and Khalatnikov, I. M. (1963).Adv. Phys.,12, 185. (The relevant part of this paper is Part II, which is an extended report, in English, of the earlier work of Lifshitz [1].)
3. Niedra, J. M. (1980). ?Gravitational Radiation in Robertson-Walker Space-Times,? dissertation, University of Pittsburgh.
4. Niedra, J. M. (preprint).
5. Grishchuk, L. P. (1974).Zh. Eksp. Teor. Fiz.,67, 825. [English transl.: (1975).Sov. Phys. JETP,40, 409.]