DIGERNES, T.; HUSSTAD, E.; VARADARAJAN, V. S. Finite approximation of Weyl systems. MATHEMATICA SCANDINAVICA, [S. l.], v. 84, n. 2, p. 261–283, 1999. DOI: 10.7146/math.scand.a-13879. Disponível em: https://tidsskrift.dk/math/article/view/13879. Acesso em: 14 aug. 2026.