Kang, Ross J., and Willem van Loon. “Tree-Like Distance Colouring for Planar Graphs of Sufficient Girth”. The Electronic Journal of Combinatorics 26, no. 1 (February 22, 2019): P1.23. Accessed March 29, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v26i1p23.