BRENKEN, Berndt. Topological quivers as multiplicity free relations. Mathematica Scandinavica, Berkeley, CA, United States, v. 106, n. 2, p. 217–242, 2010. DOI: 10.7146/math.scand.a-15134. Disponível em: https://journals.msp.org/mscand/article/view/563. Acesso em: 24 jul. 2026.