DIGERNES, T. On Classes of Projections in a von Neumann Algebra. MATHEMATICA SCANDINAVICA, [S. l.], v. 31, p. 191–200, 1972. DOI: 10.7146/math.scand.a-11424. Disponível em: https://www.mscand.dk/article/view/11424. Acesso em: 6 may. 2024.