FUGLEDE, B. Conditions for two self-adjoint operators to commute or to satisfy the Weyl relation. MATHEMATICA SCANDINAVICA, [S. l.], v. 51, p. 163–178, 1982. DOI: 10.7146/math.scand.a-11971. Disponível em: https://www.mscand.dk/article/view/11971. Acesso em: 2 may. 2024.