OCHOA, P.; RUIZ, A. J. Existence and uniqueness results for linear second-order equations in the Heisenberg group. Annales Fennici Mathematici, [S. l.], v. 42, n. 2, p. 1065–1083, 2017. DOI: 10.5186/aasfm.2017.4264. Disponível em: https://afm.journal.fi/article/view/135709. Acesso em: 20 may. 2024.