**Books:**

- R Wilson,
*Four Colors Suffice: How the Map Problem Was Solved*(Princeton University Press, Princeton, 2002).

**Articles:**

- K I Appel, Roger C Lyndon: a biographical and personal note, in K I Appel, J G Ratcliffe and P E Schupp (eds.),
*Contributions to group theory, Contemporary Mathematics***33**(Prividence, 1984), 1-10. - K I Appel, The Use of the Computer in the Proof of the Four Color Theorem,
*Proc. Amer. Philos. Soc.***128**(1) (1984), 35-39. - K I Appel and W Haken, The Nature of Proof: Limits and Opportunities,
*The Two-Year College Mathematics Journal***12**(2) (1981), 118-119. - K I Appel and W Haken, The Four Color Proof Suffices,
*The Mathematical Intelligencer***8**(1) (1986), 10-20. - Kenneth Appel, mathematician of maps, died on April 19th, aged 80,
*The Economist*(4 May 2013). - Kenneth Appel, 80; first to use a computer to prove a major math theorem,
*The Boston Globe*(30 April 2013). - D Brooks, Proving the four-color theorem expanded math's frontiers,
*University of New Hampshire Magazine Online*(Spring 2002).

http://unhmagazine.unh.edu/sp02/mathpioneers.html - M Kingston, Famed mathematician Ken Appel recalled fondly,
*Fosters.com*.

http://www.fosters.com/apps/pbcs.dll/article?AID=/20130508/GJNEWS_01/130509284 - Obituary: Kenneth I Appel (October 8, 1932 - April 19, 2013),
*Tasker Funeral Service*.

http://www.taskerfh.com/fh/obituaries/obituary.cfm?o_id=2069700&fh_id=12298 - D Overbye, Kenneth I Appel, Mathematician Who Harnessed Computer Power, Dies at 80,
*The New York Times*(28 April 2013). - R Thomas, An update on the Four Color Theorem,
*Notices Amer. Math. Soc.***45**(7) (1998), 848-859. - B Toft, Review: Four Colors Suffice: How the Map Problem Was Solved, by Robin Wilson,
*Notices Amer. Math. Soc.***51**(2) (2004), 205-207. - A Ward, Kenneth Appel Dies: Mathematician Ushered Computer Into Everyday Use,
*Newsmax*(30 April 2013). - M Weil, Kenneth Appel, mathematician who solved four-color map problem, dies at 80,
*The Washington Post*(30 April 2013).

The URL of this page is:

http://www-history.mcs.st-andrews.ac.uk/References/Appel.html