Nenya, O. I., et al. “On Sharp Conditions for the Global Stability of a Difference Equation Satisfying the Yorke Condition”. Ukrains’kyi Matematychnyi Zhurnal, vol. 60, no. 1, Jan. 2008, pp. 73–80, https://umj.imath.kiev.ua/index.php/umj/article/view/3138.