อ้างอิง ของ ทฤษฎีบทสี่สี

Appel, Kenneth & Haken, Wolfgang & Koch, John, Every Planar map is Four Colorable, Illinois: Journal of Mathematics: vol.21: pp.439-567, December 1977.
Appel, Kenneth & Haken, Wolfgang, Solution of the Four Color Map Problem, Scientific American, vol.237 no.4: pp.108-121, October 1977.
Appel, Kenneth & Haken, Wolfgang, Every Planar Map is Four-Colorable. Providence, RI: American Mathematical Society, 1989.
O'Connor and Robertson, History of the Four Color Theorem, MacTutor project, http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/The_four_colour_theorem.html
Saaty and Kainen, The Four Color Problem: Assaults and Conquest (ISBN 0-486-65092-8)
Robin Thomas, An Update on the Four-Color Theorem (PDF File) , Notices of the American Mathematical Society, Volume 45, number 7 (August 1998)
Robin Thomas, The Four Color Theorem, http://www.math.gatech.edu/~thomas/FC/fourcolor.html

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