1.El-Nabulsi RA, Anukool W. Helmholtz and Liénard-type oscillators from non-standard Lagrangians. Vietnam J. Mech. [Internet]. 2026 Mar. 29 [cited 2026 Apr. 1];48(1):1-22. Available from: https://vjs.ac.vn/vjmech/article/view/22664