Yu, Loujun, and Yuejian Peng. “A Spectral Version of the Theorem of Zykov and Erdős ”. The Electronic Journal of Combinatorics 32, no. 4 (October 17, 2025): #P4.15. Accessed May 30, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v32i4p15.