Nikandish, Reza, M. J Nikmehr, and S. M Hosseini. “On the Planarity and Perfectness of Annihilator Ideal Graphs”. Tamkang Journal of Mathematics 50, no. 4 (December 30, 2019): 361-369. Accessed September 23, 2020. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/2707.