1. Krasovskii, N.N., Teoriya upravleniya dvizheniem
(Motion Control Theory), Moscow: Nauka, 1968.
2. Zubov, V.I., Lektsii po teorii upravleniya (Lectures on
Control Theory), Moscow: Nauka, 1975.
3. Tonkov, E.L., Linear problem of optimal control of periodic solutions,
Differ. Uravn., 1976, vol. 12, no. 6,
pp. 1007–1011.
4. Ivanov, A.G., Optimal control of almost periodic motions, Prikl. Mat. Mekh., 1992, vol. 56, no. 5,
pp. 837–846.
5. Gaishun, I.V., Vvedenie v teoriyu nestatsionarnykh lineinykh
sistem (Introduction to the Theory of Time-Varying Linear Systems), Minsk: Inst.
Mat. Nats. Akad. Nauk Belarusi, 1999.