Gadіоnenkо A. Y., “On periodic motions of a pendulum with a vibrating suspension point ”, Ukr. Mat. Zhurn., vol. 18, no. 5, pp. 97–100, Aug. 1966, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/8445