JÓNSSON, Bjarni. On isomorphism types of groups and other algebraic systems. Mathematica Scandinavica, Berkeley, CA, United States, v. 5, p. 224–229, 1957. DOI: 10.7146/math.scand.a-10498. Disponível em: https://journals.msp.org/mscand/article/view/2825. Acesso em: 25 jul. 2026.