SIMMONS, H. A Possible Characterization of Generic Structures. MATHEMATICA SCANDINAVICA, [S. l.], v. 31, p. 257–261, 1972. DOI: 10.7146/math.scand.a-11432. Disponível em: https://www.mscand.dk/article/view/11432. Acesso em: 5 may. 2024.