Refahi Sheikhani, Amir Hosein, et al. “A New Three-Dimensional Chaotic System: A Single Four-Scroll Attractor”. Sigmae, vol. 6, no. 1, Aug. 2017, pp. 1-14, http://publicacoes.unifal-mg.edu.br/revistas/index.php/sigmae/article/view/496.