Appel, K.; Haken, W. The existence of unavoidable sets of geographically good configurations. (English) Zbl 0322.05141 Ill. J. Math. 20, 218-297 (1976). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 16 Documents MSC: 05C99 Graph theory 05C10 Planar graphs; geometric and topological aspects of graph theory 05C15 Coloring of graphs and hypergraphs PDF BibTeX XML Cite \textit{K. Appel} and \textit{W. Haken}, Ill. J. Math. 20, 218--297 (1976; Zbl 0322.05141) OpenURL