Nikandish, R., M. J. Nikmehr, and S. M. Hosseini. “On the Planarity and Perfectness of Annihilator Ideal Graphs”. Tamkang Journal of Mathematics, Vol. 50, no. 4, Dec. 2019, pp. 361-9, doi:10.5556/j.tkjm.50.2019.2707.