VESTERSTROM, J.; WILS, Wilbert. Direct Integrals of Hilbert Spaces II. Mathematica Scandinavica, Berkeley, CA, United States, v. 26, p. 89–102, 1970. DOI: 10.7146/math.scand.a-10968. Disponível em: https://journals.msp.org/mscand/article/view/2358. Acesso em: 25 jul. 2026.