FUGLEDE, Bent. Conditions for two self-adjoint operators to commute or to satisfy the Weyl relation. Mathematica Scandinavica, Berkeley, CA, United States, v. 51, p. 163–178, 1982. DOI: 10.7146/math.scand.a-11971. Disponível em: https://journals.msp.org/mscand/article/view/1677. Acesso em: 25 jul. 2026.