[1] G. Chen, Applications of a generalized Galerkin's method to non-linear oscillations of two-degree-of-freedom systems, Journal of Sound and Vibration, Vol. 119, No. 2, pp. 225-242, 1987.
[2] M. Bayat, I. Pakar, Shahidi, Analysis of nonlinear vibration of coupled systems with cubic nonlinearity,, Mechanika, Vol. 17, No. 6, pp. 620-629, 2011.
[3] L. Cveticanin, Vibrations of a coupled two degree-of-freedom system, Journal of Sound and Vibration, Vol. 247, No. 2, pp. 279-292, 2001.
[4] L. Cveticanin The motion of a two-mass system with non-linear connection, Journal of Sound and Vibration, Vol. 252, No. 2, pp. 361-369, 2002.
[5] S. Telli, O. Kopmaz, Free vibrations of a mass grounded by linear and non-linear springs in series, Journal of Sound and Vibration, Vol. 289, pp. 689-710, 2006.
[6] A. D. Dimarogonas, S. Haddad, 1992, Vibration for Engineers, Prentice-Hall, Englewood Cliffs, New Jersey
[7] M. T. Ahmadian, M. Mojahedi, H. Moeenfard, Free vibration analysis of a nonlinear beam using homotopy and modified Lindstedt-Poincaré methods, Journal of Solid Mechanics, Vol. 1, No. 1, pp. 29-36, 2009.
[8] Z. Guo, A. Y. Leung, H. X. Yang, Iterative homotopy harmonic balancing approach for conservative oscillator with strong odd-nonlinearity, Applied Mathematical Modelling, Vol. 35, pp. 1717-1728, 2001.
[9] J.-H. He, Homotopy perturbation technique, Computer Methods in Applied Mechanics and Engineering, Vol. 178, pp. 257-262, 1999.
[10] H. M. Sedighi, K. H. Shirazi, Dynamic pull-in instability of double-sided actuated nano-torsional switches, Acta Mechanica Solida Sinica, Vol. 28, No. 1, pp. 91-101, 2015.
[11] G. M. Ismail, M. Abul-Ez, N. M. Farea, N. Saad, Analytical approximations to nonlinear oscillation of nanoelectro-mechanical resonators, The European Physical Journal Plus, Vol. 134, pp. 47, 2019.
[12] J.-H. He, Variational iteration method-some recent results and new interpretations, Journal of Computational and Applied Mathematics, Vol. 207, No. 1, pp. 3-17, 2007.
[13] J.-H. He, A coupling method of a homotopy technique and a perturbation technique for non-linear problems, International Journal of Non-Linear Mechanics, Vol. 35, pp. 37-43, 2000.
[14] G. M. Ismail, M. Abul-Ez, M. Zayed, H. Ahmed, M. El-Moshneb, Highly accurate analytical solution for free vibrations of strongly nonlinear Duffing oscillator, Journal of Low Frequency Noise Vibration and Active Control, Vol. 41, No. 1, pp. 223–229, 2022.
[15] T. S. Amer, A. A. Galal, Vibrational dynamics of a subjected system to external torque and excitation force, Journal of Vibration and Control, Vol. 0, No. 0, pp. 1–14, 2024.
[16] K. Johannesen, The Duffing oscillator with damping for a softening potential, International Journal of Applied and Computational Mathematics, Vol. 3, pp. 3805–3816, 2017.
[17] A. H. Salas, S. A. El-Tantawy, On the approximate solutions to a damped harmonic oscillator with higher-order nonlinearities and its application to plasma physics: Semi-analytical solution and moving boundary method, European Physical Journal Plus, Vol. 135, No. 10, pp. 1–17, 2020.
[18] Y. Wu, Y.-P. Liu, Residual calculation in He’s frequency–amplitude formulation, Journal of Low Frequency Noise, Vibration and Active Control, Vol. 40, No. 2, pp. 1040–1047, 2021.
[19] Z. F. Ren, G. F. Hu, He’s frequency-amplitude formulation with average residuals for nonlinear oscillators, Journal of Low Frequency Noise, Vibration and Active Control, Vol. 38, pp. 1050–1059, 2019.
[20] N. Qie, W.-F. Houa, J.-H. He, The fastest insight into the large amplitude vibration of a string, Reports in Mechanical Engineering, Vol. 2, No. 1, pp. 1–5, 2020.
[21] J.-H. He, Amplitude–frequency relationship for conservative nonlinear oscillators with odd nonlinearities, International Journal of Applied and Computational Mathematics, Vol. 3, pp. 1557–1560, 2017.
[22] G. M. Ismail, G. M. Moatimid, M. I. Yamani, Periodic solutions of strongly nonlinear oscillators using He’s frequency formulation, European Journal of Pure and Applied Mathematics, Vol. 17, No. 3, pp. 2154-2171, 2024.
[23] G. M. Moatimid, T. S. Amer, Dynamical system of a time-delayed φ6 -Van der Pole oscillator: A non-perturbative approach, Scientific Reports, Vol. 13, pp. 11942, 2023.
[24] G. M. Moatimid, T. S. Amer, Y. Y. Ellabban, A novel methodology for a time-delayed controller to prevent nonlinear system oscillations, Journal of Low Frequency Noise, Vibration and Active Control, Vol. 43, No. 1, pp. 525-542, 2024.
[25] G. M. Moatimid, T. S. Amer, A. A. Galal, Studying highly nonlinear oscillators using the non-perturbative methodology, Scientific Reports, Vol. 13, pp. 20288, 2023.
[26] G. M. Moatimid, A. T. El‑Sayed, H. F. Salman, Different controllers for suppressing oscillations of a hybrid oscillator via non‑perturbative analysis, Scientific Reports, Vol. 14, No. 1, pp. 307, 2024.
[27] G. M. Moatimid, M. A. Mohamed, K. Elagamy, Nonlinear Kelvin-Helmholtz instability of a horizontal interface separating two electrified Walters' B liquids: A new approach, Chinese Journal of Physics, Vol. 85, pp. 629-648, 2023.
[28] G. M. Moatimid, A. Sayed, Nonlinear EHD stability of a cylindrical interface separating two Rivlin-Ericksen fluids: A Novel analysis, Chinese Journal of Physics, Vol. 87, pp. 379–397, 2024.
[29] G. M. Moatimid, Y. M. Mohamed, A novel methodology in analyzing nonlinear stability of two electrified viscoelastic liquids, Chinese Journal of Physics, Vol. 89, pp. 679-706, 2024.
[30] G. M. Moatimid, Y. M. Mohamed, A novel methodology in analyzing nonlinear stability of two electrified viscoelastic liquids, Physics of Fluids, Vol. 36, pp. 024110, 2024.
[31] G. M. Moatimid, D. M. Mostafa, M. H. Zekry, A new methodology in evaluating nonlinear Eelectrohydrodynamic azimuthal stability between two dusty viscous fluids, Chinese Journal of Physics, Vol. 90, pp. 134–154, 2024.
[32] G. M. Moatimid, D. M. Mostafa, Nonlinear stability of two superimposed electrified dusty fluids of type Rivlin-Ericksen: Non-perturbative approach, Partial Differential Equations in Applied Mathematics, Vol. 10, pp. 100745, 2024.
[33] G. M. Moatimid, M. A. Mohamed, K. Elagamy, Insightful inspection of the nonlinear instability of an azimuthal disturbance separating two rotating magnetic liquid columns, The European Physical Journal Plus, Vol. 139, pp. 590, 2024.
[34] G. M. Moatimid, T. S. Amer, A. A. Galal, Inspection of some extremely nonlinear oscillators using an inventive approach, Journal of Vibration Engineering & Technologies,, 2024.
[35] J.-H. He An improved amplitude-frequency formulation for nonlinear oscillators, International Journal of Nonlinear Sciences and Numerical Simulation, Vol. 9, pp. 211–212, 2008.