Aguiar, Marcelo, and Samuel K. Hsiao. “Canonical Characters on Quasi-Symmetric Functions and Bivariate Catalan Numbers”. The Electronic Journal of Combinatorics 11, no. 2 (February 21, 2005): R15. Accessed March 27, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v11i2r15.