@misc{10_1017_S0008439500028915,
     title = {The four-color problem, by {Oystein} {Ore.} {Academic} {Press,} {New} {York,} 1967. xv + 259 pages. $12.00.},
     journal = {Canadian mathematical bulletin},
     pages = {161--163},
     year = {1968},
     volume = {11},
     number = {1},
     doi = {10.1017/S0008439500028915},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0008439500028915/}
}