RIBENBOIM, P.; SORANI, G. Cohomology and Homology of Pairs of Preshaves. MATHEMATICA SCANDINAVICA, [S. l.], v. 22, p. 5–16, 1968. DOI: 10.7146/math.scand.a-10866. Disponível em: https://tidsskrift.dk/math/article/view/10866. Acesso em: 14 aug. 2026.