Anstee, R. P., and Linyuan Lu. “Repeated Columns and an Old Chestnut”. The Electronic Journal of Combinatorics 20, no. 4 (October 14, 2013): P2. Accessed March 15, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v20i4p2.