Domenech, Antoine, and Pascal Ochem. “Doubled Patterns With Reversal and Square-Free Doubled Patterns”. The Electronic Journal of Combinatorics 30, no. 1 (March 24, 2023): #P1.50. Accessed May 15, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v30i1p50.