KUMJIAN, Alexander. Preliminary algebras arising from local homeomorphisms. MATHEMATICA SCANDINAVICA, [S. l.], v. 52, p. 269–278, 1983. DOI: 10.7146/math.scand.a-12006. Disponível em: https://tidsskrift.dk/math/article/view/12006. Acesso em: 14 aug. 2026.