On existence of infinite-dimensional invariant tori for nonlinear countable systems of differential-difference equations. Neliniini Kolyvannya, [S. l.], v. 13, n. 2, p. 253–271, 2010. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/562. Acesso em: 10 mar. 2026.