YU, Y. A simple proof of the propagation of singularities for solutions of Hamilton-Jacobi equations . ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE, [S. l.], v. 5, n. 4, p. 439-444, 2009. DOI: 10.2422/2036-2145.2006.4.01. Disponível em: http://20.103.181.36/index.php/annaliscienze/article/view/105. Acesso em: 28 may. 2025.