S.S. Rao, V. Sundararajan, In-plane flexural vibrations of circular rings, (1969).
 J. Kirkhope, Simple frequency expression for the in‐plane vibration of thick circular rings, The Journal of the Acoustical Society of America, 59(1) (1976) 86-89.
 W. Kim, J. Chung, Free non-linear vibration of a rotating thin ring with the in-plane and out-of-plane motions, Journal of Sound and Vibration, 258(1) (2002) 167-178.
 A. Ellison, S. Yang, Natural frequencies of stators of small electric machines, in: Proceedings of the Institution of Electrical Engineers, IET, 1971, pp. 185-190.
 S.-C. Huang, W. Soedel, Effects of coriolis acceleration on the free and forced in-plane vibrations of rotating rings on elastic foundation, Journal of sound and vibration, 115(2) (1987) 253-274.
 Z. Khawly, D. Schramm, Analytical modal analysis for the stator system of a permanent magnet synchronous motor for hybrid vehicles and calculation of its natural frequencies, Proceedings of ISMA2010 Including USD2010, (2010) 4535-4548.
 M. Jin, Y. Wang, J. Pan, Vibration of circular rings coupled by elastic elements, Applied Acoustics, 148 (2019) 264-275.
 R. Yu, C. Mote Jr, Vibration and parametric excitation in asymmetric circular plates under moving loads, Journal of Sound and Vibration, 119(3) (1987) 409-427.
 Z. Li, S. Xue, Q. Ding, Preparation and Performance Test of Soldered Stators of Ultrasonic Motor, Journal of Testing and Evaluation, 45(3) (2017) 980-986.
 S. Wang, J. Xiu, S. Cao, J. Liu, Analytical treatment with rigid-elastic vibration of permanent magnet motors with expanding application to cyclically symmetric power-transmission systems, Journal of Vibration and Acoustics, 136(2) (2014).
 A. Rourke, S. McWilliam, C. Fox, Multi-mode trimming of imperfect thin rings using masses at pre-selected locations, Journal of sound and vibration, 256(2) (2002) 319-345.
 R.-C. Yu, C. Mote, Vibration of circular saws containing slots, Holz als Roh-und Werkstoff, 45(4) (1987) 155-160.
 M. Kim, J. Moon, J.A. Wickert, Spatial modulation of repeated vibration modes in rotationally periodic structures, J. Vib. Acoust., 122(1) (2000) 62-68.
 J. Chang, J. Wickert, Response of modulated doublet modes to travelling wave excitation, Journal of Sound and Vibration, 242(1) (2001) 69-83.
 J. Chang, J. Wickert, Measurement and analysis of modulated doublet mode response in mock bladed disks, in: International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, American Society of Mechanical Engineers, 2001, pp. 2239-2252.
 X. Wu, R.G. Parker, Vibration of rings on a general elastic foundation, Journal of Sound and Vibration, 295(1-2) (2006) 194-213.
 P. Bisegna, G. Caruso, Frequency split and vibration localization in imperfect rings, Journal of Sound and Vibration, 306(3-5) (2007) 691-711.
 S. Huang, W. Soedel, Response of rotating rings to harmonic and periodic loading and comparison with the inverted problem, Journal of Sound and Vibration, 118(2) (1987) 253-270.
 A. Metrikine, M. Tochilin, Steady-state vibrations of an elastic ring under a moving load, Journal of Sound and Vibration, 232(3) (2000) 511-524.
 S. Vangipuram Canchi, R.G. Parker, Parametric instability of a rotating circular ring with moving, time-varying springs, in: International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2007, pp. 809-822.
 W. Sun, S. Wang, Y. Xia, P. Zhang, Natural frequency splitting and principal instability of rotating cyclic ring structures, Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 232(1) (2018) 66-78.
 Z. Zhao, S. Wang, J. Yang, W. Chen, Parametric instability induced by traveling magnetic load within permanent magnet motors, Nonlinear Dynamics, 80(1-2) (2015) 827-843.
 Fourier transform, in: https: //en.wikipedia.org /wiki/ Fourier_transform. , 2020.