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://tidsskrift.dk/math/article/view/11432. Acesso em: 14 aug. 2026.