@article{10_4153_CJM_1967_099_6,
     author = {Synge, J. L.},
     title = {Two {Isomorphs} of the {Four-Colour} {Problem}},
     journal = {Canadian journal of mathematics},
     pages = {1084--1091},
     year = {1967},
     volume = {19},
     number = {1},
     doi = {10.4153/CJM-1967-099-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1967-099-6/}
}