Chen, He, and Xueliang Li. “Long Heterochromatic Paths in Edge-Colored Graphs ”. The Electronic Journal of Combinatorics 12, no. 1 (July 29, 2005): R33. Accessed March 27, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v12i1r33.