Every Planar Map Is Four Colorable
[Editor’s Note: The complete proof of the four-color-map theorem, as presented to the Editor of JRM consists of 56 pages of text and 114 pages of figures averaging more than 30 figures per page. A good deal of the text is couched in the rather complex mathematical terminology used by graph theorists. Presented here is Appel and Haken’s introduction to their proof and the bibliography. For a highly readable and concise description of the proof, I recommend the article by Lynn Arthur Steen in the September 1976 issue of Mathematics Magazine.