WEIBULL, T. A natural map from the ext Künneth sequence to the Tor one. MATHEMATICA SCANDINAVICA, [S. l.], v. 53, p. 203–206, 1983. DOI: 10.7146/math.scand.a-12027. Disponível em: https://www.mscand.dk/article/view/12027. Acesso em: 3 may. 2024.