GREEN, B.; TSURUGA, M.; SCOVILLE, N. A. Estimating the discrete Lusternik-Schnirelmann category. Topological Methods in Nonlinear Analysis, [S. l.], v. 45, n. 1, p. 103–116, 2015. DOI: 10.12775/TMNA.2015.006. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2015.006. Acesso em: 4 oct. 2022.