“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” (2003) Neliniini Kolyvannya, 6(2), pp. 260–278. Available at: https://nosc.imath.kiev.ua/index.php/nosc/article/view/265 (Accessed: 12 April 2026).