HARARY, Frank; WILCOX, Gordon W. Boolean Operations on Graphs. Mathematica Scandinavica, Berkeley, CA, United States, v. 20, p. 41–51, 1967. DOI: 10.7146/math.scand.a-10817. Disponível em: https://journals.msp.org/mscand/article/view/2509. Acesso em: 25 jul. 2026.