On Frechet differentiability of invariant torus for nonlinear countable system of difference equations defined on an infinite-dimensional torus and containing deviations of the discrete argument. Neliniini Kolyvannya, [S. l.], v. 6, n. 2, p. 260–278, 2003. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/265. Acesso em: 22 jan. 2026.