Nomura, Kazumasa, and Paul Terwilliger. “The Norton-Balanced Condition for $Q$-Polynomial Distance-Regular Graphs”. The Electronic Journal of Combinatorics 32, no. 1 (March 28, 2025): P1.49. Accessed March 27, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v32i1p49.