1.
Elnazarov AA, Samoilenko AM. On invariant tori of countable systems of differential equations with delay. Ukr. Mat. Zhurn. [Internet]. 1999 Sep. 25 [cited 2025 Dec. 5];51(9):1292–1295. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/4726