Gronau, Detlef, and Maciej Sablik. “A Functional Equation Arising from an Asymptotic Formula for Iterates”. Annales Mathematicae Silesianae 8 (September 30, 1994): 173-187. Accessed May 19, 2024. https://www.journals.us.edu.pl/index.php/AMSIL/article/view/14233.