BRANDES, Ulrik; PAMPEL, Barbara. Orthogonal-Ordering Constraints are Tough. Journal of Graph Algorithms and Applications, [S. l.], v. 17, n. 1, p. 1–10, 2013. DOI: 10.7155/jgaa.00281. Disponível em: http://jgaa-v4.cs.brown.edu/index.php/jgaa/article/view/paper281. Acesso em: 2 jul. 2024.