MORENO, José Pedro; SEEGER, Alberto. External analysis of boundary points of convex sets: illumination and visibility. Mathematica Scandinavica, Berkeley, CA, United States, v. 105, n. 2, p. 265–286, 2009. DOI: 10.7146/math.scand.a-15118. Disponível em: https://journals.msp.org/mscand/article/view/579. Acesso em: 24 jul. 2026.