Whitney, Hassler; Tutte, W. T. Kempe chains and the four colour problem. (English) Zbl 0253.05120 Util. Math. 2, 241-281 (1972). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 2 ReviewsCited in 8 Documents MSC: 05C10 Planar graphs; geometric and topological aspects of graph theory 05C15 Coloring of graphs and hypergraphs 57M15 Relations of low-dimensional topology with graph theory 05-04 Software, source code, etc. for problems pertaining to combinatorics PDF BibTeX XML Cite \textit{H. Whitney} and \textit{W. T. Tutte}, Util. Math. 2, 241--281 (1972; Zbl 0253.05120)