Gyárfás, András, and Manouchehr Zaker. “On $(\delta, \chi)$-Bounded Families of Graphs”. The Electronic Journal of Combinatorics 18, no. 1 (May 8, 2011): P108. Accessed March 17, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v18i1p108.