The Four-Color Theorem : History

This elegant little book discusses the famous problem concerning the minimum number of colors required to print a map such that no two adjoining countries have the same color, no matter how convoluted the boundaries; this is one of the problems that came to define the field now known as topology. The book begins by discussing the history of the problem, and then goes into the mathematics, pleasantly enough that anyone with an elementary knowledge of geometry can follow it, but with enough rigor that a mathematician can also read it with pleasure.