Boutin, Debra, and Wilfried Imrich. “Infinite Graphs With Finite 2-Distinguishing Cost”. The Electronic Journal of Combinatorics 21, no. 4 (December 11, 2014): #P4.52. Accessed May 30, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v21i4p52.