B-Coloring of Series-Parallel Graphs: Exact Cactus Values, Extremal K2,r Bundles, and the 2Δ Frontier. EKSAKTA [Internet]. 2026 Oct. 30 [cited 2026 Oct. 31];27(05):1052-69. Available from: https://eksakta.ppj.unp.ac.id/index.php/eksakta/article/view/755