SANDGREN, Lennart. On convex cones. MATHEMATICA SCANDINAVICA, [S. l.], v. 2, p. 19–28, 1954. DOI: 10.7146/math.scand.a-10390. Disponível em: https://tidsskrift.dk/math/article/view/10390. Acesso em: 14 aug. 2026.