Brzozowski, Janusz, and Corwin Sinnamon. “Complexity of Right-Ideal, Prefix-Closed, and Prefix-Free Regular Languages”. Acta Cybernetica 23, no. 1 (January 1, 2017): 9-41. Accessed March 29, 2024. https://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3913.