FEDERICO, S. Local Solvability of a Class of Degenerate Second Order Operators. Bruno Pini Mathematical Analysis Seminar, [S. l.], v. 8, n. 1, p. 185–203, 2017. DOI: 10.6092/issn.2240-2829/8172. Disponível em: https://mathematicalanalysis.unibo.it/article/view/8172. Acesso em: 8 may. 2024.