CARLSEN, Toke Meier; WINGER, Marius Lie. Orbit equivalence of graphs and isomorphism of graph groupoids. Mathematica Scandinavica, Berkeley, CA, United States, v. 123, n. 2, p. 239–248, 2018. DOI: 10.7146/math.scand.a-105087. Disponível em: https://journals.msp.org/mscand/article/view/261. Acesso em: 24 jul. 2026.