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2. K. A. Karacharov and A. G. Pilyutik, Introduction to the Technical Theory of Motion Stability [in Russian], Fizmatgiz, Moscow (1972).
3. F. D. Bairamov, ?Technical stability in a system having distributed parameters subject to constantly acting perturbations,? Izv. Vyssh. Uchebn. Zaved., Aviats. Tekh., No. 2 (1974).
4. T. K. Sirazetdinov, ?The Lyapunov-function method in researching processes with after effects,? in: A Direct Method with Applications in Stability Theory [in Russian], Nauka, Novosibirsk (1981).
5. N. F. Kirichenko, Some Aspects of Motion Stability and Controllability [in Russian], Izd. Kiev. Univ., Kiev (1972).