DIDIMO, Walter; PIZZONIA, Maurizio. Upward Embeddings and Orientations of Undirected Planar Graphs. Journal of Graph Algorithms and Applications, [S. l.], v. 7, n. 2, p. 221–241, 2003. DOI: 10.7155/jgaa.00068. Disponível em: https://jgaa.info/index.php/jgaa/article/view/paper68. Acesso em: 30 jun. 2024.