LE SUAN KAN. On construction of approximate solutions for an autonomous difference second order equation describing oscillating processes with a considerable resistance force. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 6, p. 778–781, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8626. Acesso em: 6 dec. 2025.