KLEE, V. L. Jr. The structure of semispaces. MATHEMATICA SCANDINAVICA, [S. l.], v. 4, p. 54–64, 1956. DOI: 10.7146/math.scand.a-10455. Disponível em: https://tidsskrift.dk/math/article/view/10455. Acesso em: 14 aug. 2026.