LagodaV. A., ParasyukI. O., and SamoilenkoA. M. “Lipschitzian Invariant Tori of Indefinite Monotone System”. Ukrains’kyi Matematychnyi Zhurnal 64, no. 3 (March 25, 2012): 363-383. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/2582.