Abiad A, Haemers WH. Cospectral Graphs and Regular Orthogonal Matrices of Level 2. Electron. J. Combin. [Internet]. 2012Aug.9 [cited 2026Apr.4];19(3):P13. Available from: https://www.combinatorics.org/ojs/index.php/eljc/article/view/v19i3p13