FISCELLA, A.; SERVADEI, R.; VALDINOCI, E. Density properties for fractional Sobolev spaces. Annales Fennici Mathematici, [S. l.], v. 40, n. 1, p. 235–253, 2015. DOI: 10.5186/aasfm.2015.40xx. Disponível em: https://afm.journal.fi/article/view/135539. Acesso em: 30 oct. 2024.