Four-color problem.

Every planar map is four colorable / by: (Language materials, printed)

The four color theorem : = history, topological foundations, and idea of proof / by: (Language materials, printed)

A Kaleidoscopic view of graph colorings by: (Electronic resources)

Graph theory.

Graph Theory.

Four-color problem.

Combinatorics.

Applications of Mathematics.

Graph coloring.

Mathematics.