Gadіоnenkо A. Y. On periodic motions of a pendulum with a vibrating suspension point . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 18, n. 5, p. 97–100, 1966. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8445. Acesso em: 6 dec. 2025.