Xu, Rui, and Cun-Quan Zhang. “Nowhere-Zero 3-Flows in Squares of Graphs”. The Electronic Journal of Combinatorics 10, no. 1 (January 22, 2003): R5. Accessed March 17, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v10i1r5.