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. НК [Internet]. 2003 Jun. 29 [cited 2026 Jan. 22];6(2):260-78. Available from: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/265