Hrod, I. M., and V. L. Kulik. “On Local Perturbations of Linear Extensions of Dynamical Systems on a Torus”. Ukrains’kyi Matematychnyi Zhurnal 52, no. 2 (February 25, 2000): 282–287. Accessed April 11, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/4417.