RIBENBOIM, P.; SORANI, G. Cohomology and Homology of Pairs of Preshaves. Mathematica Scandinavica, Berkeley, CA, United States, v. 22, p. 5–16, 1968. DOI: 10.7146/math.scand.a-10866. Disponível em: https://journals.msp.org/mscand/article/view/2435. Acesso em: 25 jul. 2026.