Yip, Martha. “Rook Placements and Jordan Forms of Upper-Triangular Nilpotent Matrices”. The Electronic Journal of Combinatorics 25, no. 1 (March 29, 2018): #P1.68. Accessed April 24, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v25i1p68.