GONÇALVES, Daniel. Not all planar graphs are in PURE-4-DIR. Journal of Graph Algorithms and Applications, [S. l.], v. 24, n. 3, p. 293–301, 2020. DOI: 10.7155/jgaa.00533. Disponível em: http://jgaa-v4.cs.brown.edu/index.php/jgaa/article/view/paper533. Acesso em: 2 jul. 2024.