1. G. A. Leonov, “Phase synchronization. Theory and applications,” Avtom. Telemekh. 10, 47–85 (2006).
2. G. A. Leonov, “Lyapunov’s second method in the theory of phase synchronization,” Prikl. Mat. Mekh. 40, 238–244 (1976).
3. A. Kh. Gelig, G. A. Leonov, and V. A. Yakubovich, Stability of Nonlinear Systems with a Nonunique Equilibrium State (Nauka, Moscow, 1978) [in Russian].
4. B. I. Konosevich and Yu. B. Konosevich, “Sufficient global stability condition for a model of the synchronous electric motor under nonlinear load moment,” Vestn. St. Petersburg Univ.: Math. 51, 57–65 (2018). https://doi.org/10.3103/S1063454118010053
5. F. Tricomi, “Integrazione di unequazione differenziale presentasi in electrotechnica,” Ann. Della Roma Schuola Norm. Super. Pisa 2 (2), 1–20 (1933).