Martin, Jeremy L., and Jennifer D. Wagner. “Updown Numbers and the Initial Monomials of the Slope Variety”. The Electronic Journal of Combinatorics 16, no. 1 (July 9, 2009): R82. Accessed March 16, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v16i1r82.