AUDRITO, A.; FELIPE-NAVARRO, J.-C. .; ROS-OTON, X. . The Neumann problem for the fractional Laplacian: regularity up to the boundary. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE, [S. l.], v. 24, n. 2, p. 1155-1222, 2023. DOI: 10.2422/2036-2145.202105_096. Disponível em: https://journals.sns.it/index.php/annaliscienze/article/view/5767. Acesso em: 20 feb. 2026.