BOVE, Antonio. Hypoellipticity and Non Hypoellipticity for Sums of Squares of Complex Vector Fields. Bruno Pini Mathematical Analysis Seminar, [S. l.], v. 2, n. 1, 2011. DOI: 10.6092/issn.2240-2829/2665. Disponível em: https://mathematicalanalysis.unibo.it/article/view/2665. Acesso em: 23 nov. 2024.