In \([1]\) it is proved that each \(4\)-critical plane graph contains either a \(4\)- or a \(5\)-cycle or otherwise a face of size between \(6\) and \(11\).
Citation
O.V. Borodin. To the paper of H.L. Abbott and B. Zhou on \(4\)-critical Planar Graphs[J], Ars Combinatoria, Volume 043. 191-192. DOI: .
