VESTERSTROM, J.; WILS, Wilbert. Direct Integrals of Hilbert Spaces II. MATHEMATICA SCANDINAVICA, [S. l.], v. 26, p. 89–102, 1970. DOI: 10.7146/math.scand.a-10968. Disponível em: https://tidsskrift.dk/math/article/view/10968. Acesso em: 14 aug. 2026.