Edwards, Keith, and Graham Farr. “Improved Upper Bounds for Planarization and Series-Parallelization of Degree-Bounded Graphs”. The Electronic Journal of Combinatorics 19, no. 2 (May 31, 2012): #P25. Accessed April 12, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v19i2p25.