Yen, Lily. “Crossings and Nestings for Arc-Coloured Permutations and Automation”. The Electronic Journal of Combinatorics 22, no. 1 (January 20, 2015): P1.14. Accessed March 28, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v22i1p14.