Binucci, Carla, Emilio Di Giacomo, Walter Didimo, and Aimal Rextin. “Switch-Regular Upward Planarity Testing of Directed Trees”. Journal of Graph Algorithms and Applications 15, no. 5 (October 1, 2011): 587–629. Accessed December 22, 2024. https://jgaa-v4.cs.brown.edu/index.php/jgaa/article/view/paper241.