PALMÉR, I. The global homological dimension of semi-trival extensions of rings. MATHEMATICA SCANDINAVICA, [S. l.], v. 37, p. 223–256, 1975. DOI: 10.7146/math.scand.a-11603. Disponível em: https://www.mscand.dk/article/view/11603. Acesso em: 6 may. 2024.