The four-color problem /
Ore, Oystein
The four-color problem / Oystein Ore. - New York : Academic Press, 1968. - xv, 259 p : ill. - Monographs and textbooks in pure and applied mathematics 27 .
Bibliography: p. 249-253
Four-color problem
The four-color problem / Oystein Ore. - New York : Academic Press, 1968. - xv, 259 p : ill. - Monographs and textbooks in pure and applied mathematics 27 .
Bibliography: p. 249-253
Four-color problem