Cariolaro, David, and Gianfranco Cariolaro. “Colouring the Petals of a Graph”. The Electronic Journal of Combinatorics 10, no. 1 (January 29, 2003): R6. Accessed March 17, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v10i1r6.