AteiwiA. M. “On the Problem on Periodic Solutions of One Class of Systems of Difference Equations”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 2 (February 25, 1997): 309–314. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5008.