Graham, R. L., and B. D. Lubachevsky. “Repeated Patterns of Dense Packings of Equal Disks in a Square”. The Electronic Journal of Combinatorics 3, no. 1 (April 20, 1996): R16. Accessed March 31, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v3i1r16.