Mohiaddin, Gohdar H., and Khidir R. Sharaf. “Null Spaces Dimension of the Eigenvalue -1 in a Graph”. Science Journal of University of Zakho 7, no. 4 (December 30, 2019): 167–171. Accessed November 22, 2024. https://sjuoz.uoz.edu.krd/index.php/sjuoz/article/view/609.