Zhai, Mingqing, Ruifang Liu, and Jie Xue. “A Unique Characterization of Spectral Extrema for Friendship Graphs”. The Electronic Journal of Combinatorics 29, no. 3 (August 12, 2022): #P3.32. Accessed May 15, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v29i3p32.