Liu, Qi, and Douglas B. West. “Tree-Thickness and Caterpillar-Thickness under Girth Constraints”. The Electronic Journal of Combinatorics 15, no. 1 (July 21, 2008): R93. Accessed March 27, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v15i1r93.