Cheng, Kam Hang, Yik Man Chiang, and Avery Ching. “D-Module Approach to Liouville’s Theorem for Difference Operators”. New Zealand Journal of Mathematics 53 (October 25, 2022): 63–79. Accessed April 20, 2024. https://nzjmath.org/index.php/NZJMATH/article/view/187.