1. N. G. Chetaev, The Stability of Motion [in Russian], Nauka, Moscow (1965).
2. E. E. Zajac, ?The Kelvin-Tait-Chetaev theorem and extensions,? J. Astronautical Sci.,11, No. 2, 46?49 (1964).
3. A. I. Miloslavskii, ?On justification of the spectral approach in nonconservative problems of the theory of elastic stability,? Funkts. Anal. Prilozhen.,17, No. 3, 83?84 (1983).
4. V. N. Zefirov, V. V. Kolesov, and A. I. Miloslavskii, ?A study of the natural frequencies of a rectilinear pipeline,? Izv. Akad. Nauk SSSR, Mekh. Tverd. Tela, No. 1, 179?188 (1985).
5. A. I. Miloslavskii, ?On the stability of viscoelastic systems,? in: All-union Science Conference: The Method of A. M. Lyapunov's Functions in Contemporary Mathematics, May 27?29, 1986, Theses of Reports [in Russian], Kharkov (1986), p. 118.