Ospan, T. M., A. B. Kydyrbekuky, and G.-G. A. E. Ibraev. “Resonant Phenomena in Nonlinear Vertical Rotor Systems”. Journal of Mathematics, Mechanics and Computer Science, vol. 112, no. 4, Dec. 2021, doi:10.26577/JMMCS.2021.v112.i4.05.