Albert, Michael, Cheyne Homberger, and Jay Pantone. “Equipopularity Classes in the Separable Permutations”. The Electronic Journal of Combinatorics 22, no. 2 (April 14, 2015): P2.2. Accessed March 29, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v22i2p2.