MORENO, J. P.; SEEGER, A. External analysis of boundary points of convex sets: illumination and visibility. MATHEMATICA SCANDINAVICA, [S. l.], v. 105, n. 2, p. 265–286, 2009. DOI: 10.7146/math.scand.a-15118. Disponível em: https://www.mscand.dk/article/view/15118. Acesso em: 3 may. 2024.