Bose, Prosenjit, Hazel Everett, Sándor Fekete, Michael Houle, Anna Lubiw, Henk Meijer, Kathleen Romanik, et al. 1998. “A Visibility Representation for Graphs in Three Dimensions”. Journal of Graph Algorithms and Applications 2 (3):1-16. https://doi.org/10.7155/jgaa.00006.