Singularities of Solutions to Cauchy Problems for Semilinear Wave Equations in Two Space Dimensions. Journal of Partial Differential Equations, [S. l.], v. 3, n. 1, p. 69–80, 1990. Disponível em: https://global-sci.com/index.php/jpde/article/view/3652. Acesso em: 5 dec. 2025.