Gvozdjak, Pavol, Horák, Peter, Meszka, Mariusz, and Skupień, Zdzislaw. “Strong Chromatic Index for Multigraphs”. Utilitas Mathematica 57 (May 9, 2000). Accessed May 8, 2026. https://utilitasmathematica.com/index.php/Index/article/view/189.