HANSEN, S. On configurations in 3-space without elementary planes and on the number of ordinary planes. MATHEMATICA SCANDINAVICA, [S. l.], v. 47, p. 181–194, 1980. DOI: 10.7146/math.scand.a-11884. Disponível em: https://www.mscand.dk/article/view/11884. Acesso em: 9 may. 2024.