Kündgen A, Mendelsohn E, Voloshin V. Colouring Planar Mixed Hypergraphs. Electron. J. Combin. [Internet]. 2000Sep.28 [cited 2026Mar.16];7(1):R60. Available from: https://www.combinatorics.org/ojs/index.php/eljc/article/view/v7i1r60