Kydyrbekuly, A. B., and G. A. Ibrayev. “The Self-Oscillation in the Vertical Rotor System Mounted on Elastic Supports”. Journal of Mathematics, Mechanics and Computer Science, vol. 105, no. 1, Apr. 2020, pp. 160-73, doi:10.26577/JMMCS.2020.v105.i1.14.