MARRIOTT, Kim; STUCKEY, Peter. NP-Completeness of Minimal Width Unordered Tree Layout. Journal of Graph Algorithms and Applications, [S. l.], v. 8, n. 3, p. 295–312, 2004. DOI: 10.7155/jgaa.00093. Disponível em: https://jgaa-v4.cs.brown.edu/index.php/jgaa/article/view/paper93. Acesso em: 7 jun. 2025.