KRISTENSEN, L. On the Cohomology of Spaces with Two Non-Vanishing Homotopy Groups. MATHEMATICA SCANDINAVICA, [S. l.], v. 12, p. 83–105, 1963. DOI: 10.7146/math.scand.a-10674. Disponível em: https://www.mscand.dk/article/view/10674. Acesso em: 16 apr. 2024.