JÓNSSON, B. On isomorphism types of groups and other algebraic systems. MATHEMATICA SCANDINAVICA, [S. l.], v. 5, p. 224–229, 1957. DOI: 10.7146/math.scand.a-10498. Disponível em: https://www.mscand.dk/article/view/10498. Acesso em: 5 may. 2024.