1. V. M. Alekseev, V. M. Tikhomirov, and S. V. Fomin, Optimal Control [in Russian], Nauka, Moscow (1979).
2. P. P. Andreyanov and K. E. Dushin, “An approach to the study of bifurcation sets in the Kovalevskaya–Yehia problem,” in: Proc. XI Int. Conf. “Stability, Control, and Dynamics of Rigid Bodis,” Donetsk (2011), pp. 11–12.
3. P. P. Andreyanov and K. E. Dushin, “Bifurcation sets in the Kovalevskaya–Yehia problem,” Mat. Sb., 203, No. 4, 3-46 (2012).
4. G. G. Appelrot, “Incompletely symmetric heavy gyroscopes,” in: Motion of a Rigid Body around a Fixed Point, Moscow–Leningrad (1940), pp. 61–156.
5. O. I. Bogoyavlensky, “Integrable Euler equations on Lie algebras arising in problems of mathematical physics,” Izv. Akad. Nauk SSSR, Ser. Mat., 48, No. 5, 883–938 (1984).