LIU, Q.; ZHOU, X. Horizontal convex envelope in the Heisenberg group and applications to sub-elliptic equations. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE, [S. l.], v. 22, n. 4, p. 2039-2076, 2021. DOI: 10.2422/2036-2145.201907_001. Disponível em: https://journals.sns.it/index.php/annaliscienze/article/view/886. Acesso em: 20 feb. 2026.