NG, K.-C. THE NONLINEAR CAUSTIC. Tamkang Journal of Mathematics, [S. l.], v. 22, n. 4, p. 353–370, 1991. DOI: 10.5556/j.tkjm.22.1991.4624. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/4624. Acesso em: 5 may. 2024.