Albertson, Michael O., Daniel W. Cranston, and Jacob Fox. “Crossings, Colorings, and Cliques”. The Electronic Journal of Combinatorics 16, no. 1 (April 3, 2009): #R45. Accessed May 2, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v16i1r45.