BischiGian-Italo, Laura Gardini, and Christian Mira. “Unbounded Not Diverging Trajectories in Maps With a Vanishing Denominator”. Annales Mathematicae Silesianae 13 (September 30, 1999): 91-102. Accessed January 22, 2025. https://journals.us.edu.pl/index.php/AMSIL/article/view/14140.