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2. E. A. Barbashin, Introduction to the Theory of Stability, Wolters-Noordhoff, Groningen (1970).
3. B. P. Demidovich, Lectures on Mathematical Theory of Stability [in Russian], Nauka, Moscow (1967).
4. V. A. Ivanov, B. K. Chemodanov, and V. S. Medvedev, Mathematical Fundamentals of Automatic Control Theory [in Russian], Vyshaya Shkola, Moscow (1971).
5. A. N. Krylov, Ship Vibration, Vol. 10 of Collected Works [in Russian], AN SSSR, Moscow–Leningrad (1948).