Poshni, Mehvish I., Imran F. Khan, and Jonathan L. Gross. “Genus Distributions of 4-Regular Outerplanar Graphs”. The Electronic Journal of Combinatorics 18, no. 1 (October 31, 2011): P212. Accessed March 17, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v18i1p212.