AARNES, J. F.; ANDENAES, P. R. On Nets and Filters. Mathematica Scandinavica, Berkeley, CA, United States, v. 31, p. 285–292, 1972. DOI: 10.7146/math.scand.a-11435. Disponível em: https://journals.msp.org/mscand/article/view/2210. Acesso em: 25 jul. 2026.