M, J., A. N, and V. Aboites. “Shift of Saddle-Node Bifurcation Points in Modulated Hénon Map”. Revista Mexicana De Física, vol. 48, no. 4, Jan. 2002, pp. 290-0, https://rmf.smf.mx/ojs/index.php/rmf/article/view/3065.