JACOBSSON, C. On the double Poincaré series of the enveloping algebras of certain graded Lie algebras. MATHEMATICA SCANDINAVICA, [S. l.], v. 51, p. 45–58, 1982. DOI: 10.7146/math.scand.a-11963. Disponível em: https://www.mscand.dk/article/view/11963. Acesso em: 5 may. 2024.