MAHMOUD, I.; NAOUI, kamel; JEMMALI, H. Study of Speculative Bubbles: The Contribution of Approximate Entropy. International Journal of Economics and Financial Issues, [S. l.], v. 3, n. 3, p. 683–693, 2013. Disponível em: https://econjournals.com/index.php/ijefi/article/view/443. Acesso em: 18 may. 2022.